A NEW AND IMPROVED SYSTEM OF HYGROMETERS AND OTHER ANALOGOUS INSTRUMENTS AND OF THE COMPOSITION OF THEIR HYGROSCOPIC ORGANS
Year: 1884

page_text: I, PETER CALLIBURCES of Boulevard St Michel No 3, Paris, France, Doctor of
Medicine, do hereby declare the nature of said invention for "A NEW AND IMPROVED
SYSTEM OF HYGROMETERS AND OTHER ANALOGOUS INSTRUMENTS AND OF THE
COMPOSITION OF THEIR HYGROSCOPIC ORGANS" and in what manner the same is
to be performed to be particularly described and ascertained in and by the following
statement:-
The principle, upon which is based this system of hygrometers and other
analogous instruments and of the composition of their hygroscopic organ or organs
is the following:-to employ as a bygroscopic organ (or as hygroscopic organs) one
spring (or several), (of the form required by the disposition to be given to the
hygrometer or other analogous instrument), prepared by the combination of any
clastic and non hygroscopic substance whatsoever (for example, india-rubber, steel,
silver, gold alloying with any other elastic metal), or slightly hygroscopic substance
whatever (ns, for example, leather) with any hygroscopic substance whatever (or
with several such substances) for example, starch pasto, gelatiné and any substance
which contains gelatine, the different strong glues, dissolved gum-arabic, and any
other gum having the property of absorbing moisture, different vegetable juices
(for example, the juice of garlic, tho juices of different flowers, the sap of different
plants), the diastasis, the dextrine, the legumine, the caseine dissolved in a feeblo
acid or in water saturated with borax, or in gastric juice, either natural or artificial,
the white of egg, and animal or vegetable albumen in general, and any substance
which contains it, milk, blood, sperm, the secretion of the mucous membranes, the
secretion of the salivary glands, the mucous secreted by snails, the crystalline lens
and the cornea, triturated or dissolved in natural or artificial gastric juice, the
albuminous matter secreted by the oviducts of the frog, the substance of the brain
and also of the nerves, fibrine and gluten dissolved in natural or artificial gastric
juice, protoplasm (for example, the acthalium septicum, the hyphaena candida),
ivory, whale bone, shell, horn, the substance which forms the quills of feathers,
wood, and, in general, all substances having the property of absorbing moisture
and of drying gradually..

page_text: In preparing the hygroscopic organ I combine the elastic and non-hygroscopic
(or slightly hygroscopic) substance with the hygroscopic substance in such a manner
as to allow the moisture to act only upon a part of the surface of the hygroscopic
organ (the part which is formed by the hygroscopic substance) thus producing
displacements of all the points of the hygroscopic organ, while the remainder of
the latter rests entirely insensible to the action of moisture. Consequently, all tho
points of the hygroscopic organ are displaced, under this action, in proportion to
the degree of moisture.
An index, bearing upon a proper point of the hygroscopic organ traverses a space
proportioned to the sum of the partial displacements of all the points of tho
hygroscopic organ, and thus indicates, upon a dial, by a proportional angle, the
degree of moisturo. I have called the hygroscopic organs prepared according to the
principle set forth above "Heterhygroscopic springs" or "Compound Hygrometric
springs" and tho hygrometers which bear such springs " Heterhygroscopic hygro-
meters."
The following description of some types of the hygrometers of this system will
render the principle upon which the system is based perfectly clear. A tube of
india-rubber is cut in the form of a helix, A, B, Figure 1, between the spires of
which are free spaces. This helix is plastered on its convex face only with a
hygroscopic substance (for example, with a solution of cascine); it is suspended by
one of its extremities in the interior of a glass-tube, CD, closed above and below.
The inferior, enlarged, part of the tube bears the divided circle, E; n very light
index, F, horizontally attached to the inferior (or free) extremity of the helix
indicates the hygrometric degrees. A metallic axis, G, around which the index
freely turns, is fixed in the middle of a small cross-bar, E, fixed under the index.
In another type a light circle made of paper, bearing the hygrometric scale, is
suspended at the lower extremity of the helix; a fixed indicator points out the
hygrometric degrees upon the graduated turning circle. In order that one may
suspend the helix from the middle of the tube, the hygrometer of this type is
provided at its superior extremity with a fastening, I, so arranged as to be cusily
opened and shut. The instrument is provided with thermometer, JK, indicating
the interior temperature of the tube. A thermometer can also be combined with
any other type of hygrometers of this systein.
From this arrangement it results that when the moisture acts upon the belix,
this physical agent acts only on the hygroscopic part of the spring, that is to say
only on its convox face; the spires of the helix thus tend to bend more, and all the
points of the helix displace themselves in the same direction; the sum of all theso
clementary displacements reunite at the last spire, which transmits them to the
index, F. A circulatory movement is thus communicated to this latter (such as the
helix would have if it should be turned in order to scrow it as one would fix a
screw), which turns toward the point of extreme moisture. When the moisture
diminishes, each of the spires of the helix tends to flatten and all of the helix to
unroll. Consequently the displacements of all tho points of the helix which result
then have the opposite direction to that which they had previously, and thus impart
to the index a circulatory movement toward the point of extreme dryness. If,
instead of rendering hygroscopic the convex face of the helix, its concave face
should be made sensible to the action of moisture, this action would then produce
displacements of all points of the helix in the opposite direction. The heter-
hygroscopic spring (of whatever form) of the instrument (of whatever type) is
either shut up in a cavity (as described above), or exposed to the open air. In the
first case the cavity may either be constantly closed or it may be provided with an
opening furnished with a stopper of any kind which will allow it to be easily
opened and shut. The cavity of the instrument is constantly closed when the
hygrometer is destined to serve either to demonstrate in lectures on Physics the
influence of thermometric variatious upon hygrometric indications, or like the
thermometer for low temperatures, or to compare these indications with those of a
hygrometer with a heterhygroscopic spring exposed to the open air. The cavity of

page_text: A
the instrument is provided with an opening furnished with a fastening which can
be easily opened and shut, when the instrument is destined to serve the following
purposes: 1° to determine the quantity of moisture produced in a given time by a
restricted surface (for example, by a portion of the skin) and where it is necessary
that the moisture produced should enter the cavity of the instrument (from which
all moisture has been previously removed, or in which only a known quantity of
moisture is left) and should remain there during the observation. Thus, the
instrument has this arrangement when it is destined to be employed in Medicine
("Medical hygrometer" or "Diapnoometer") in order to determine in a physiological
point of view the degree of perspiration of the different parts of the skin, as well
as to observo in clinical examinations the state of the breathing of the sick, and
the variations of the same. The fastening, with which the opening of the cavity
of the instrument is provided, is either a cock, or a fastening having the following
arrangement: Two round superposed plates (forced, by means of a spring and a
screw, which are found in the centre of the two plates, to be applied with a certain
force one against the other) are provided with three openings, one of which is in
the superior plate and two in the inferior. At the opening of the superior plate tho
cavity of the instrument is fastened at its opon end. At one of the two openings
of the inferior plate a little vase is screwed in which is chloride of calcium; the
other of these two openings is free and it is by this latter opening that the instru-
ment is applied to that part of the skin destined to bo examined in a hygrometric
point of view. From this arrangement it results that in turning the superior plate
around its centre one can sometimes put the cavity of the instrument in communi-
cation either with the small vase (which is taken away when the instrument is
to be applied to the skin) containing chloride of calcium, or with the free opening
(of the inferior plate), applied to the skin, sometimes shut it, in conducting it to a
full part of the inferior plate. To remove the moisture from the cavity of the
instrument I employ also, before making the observation, the following means.
small vase with two mouths containing chloride of calcium communicates with the
cavity of the instrument by means of two india-rubber tubes; one of these tubos
benring a flask of india-rubber (provided with two valves so arranged that when
the flask is compressed, one of the valves opens, and allows the passage of air to
the cavity of the instrument, and the other closes, and when the flask dilates, the
first valve shuts and the second opens) puts the small vase, by means of one of its
mouths, in communication with the cavity of, the instrument; the other tubo puts
the cavity of the instrument into communication with the small vase by the other
mouth of the latter. Thus, by alternately compressing and slackening the flask,
the air is made to circulate through the small vase (from which the dry air passes
to the cavity of the instrument) and the cavity of the instrument (from which tho
moisture passes to the small vase and there becomes dry) and in this way the
moisture is rapidly removed from the cavity of the instrument. 2°. When the
instrument (Hygrotropium) is designed for hygroscopic examination of different
kinds of organic substances. In this case it is disposed in the following manner:
Its cavity is formed of a glass cylinder having throughout the same diameter and
provided at its upper extremity with a cover (which may be easily removed) having
in its interior, at the centre, a screw to which one suspends the helix, of india-
rubber, one of whose faces (for example, the convex face) is coated with the
substanco which is to be the object of the examination. In the inferior opening of
the cylinder is placed a cross-bar (occupying the entire diameter of the cylinder),
in the middle of which is fixed, vertically, a steel axis, occupying the entire axis
of the cylinder. When observations requiring great precision are to be taken, the
helix is hung free, having no axis. The cylinder is fixed vertically, by its inferior
extremity, upon a round turning-plate, which has in one of its halves an opening
corresponding to that of the cylinder. Under this plate is found another provided
with two openings, one of which communicates with a small vase in which chlorido
of calcium (or concentrated sulphuric acid) is put and the other with a small vase
containing water. The two plates have at their contres a screw and a spring

page_text: which oblige them to press one against the other with a certain force. In this
way, by turning the superior plate, the cavity of the cylinder is brought into
communication sometimes with the small vase whose interior air is completely dry,
sometimes with the other small vase containing air saturated with moisture, some-
times with a full part of the lower plate. The upper plate has on the side opposite
to that where the cylinder is fixed a cover (with a cock in its centre), which can be
easily removed and which is designed to allow of the introduction into cach of the
two little vases of the substance which the experiment requires and also of its
complete removal. For the same purpose, each of the two little vases has a cock
in the lower part of its wall. The instrument is provided with two dials, one for
ench of the two indices of the helix. One can thus, if the substance with which
the helix is coated is hygroscopic, make the index, which is attached to the
inferior or free extremity of the helix, as well as that which is attached to one of
the superior spires of the helix (and showing the number of turns made by the
first index) move either towards the point of extreme moisture (by putting the
cylinder of the instrument into communication with the small vase which contains
water, or towards the point of extreme dryness (by putting the cylinder into
communication with the other small vase). One can thus not only see whether
the substance with which the helix is coated is hygroscopic or not, but can also
determine the degree of its hygroscopic property by comparing the time required
by the indices to traverse in the moisture a fixed distance upon the dial with the
time required to traverse the same space in dryness. If the substance with which
the helix is coated is not hygroscopic, the indices remain motionless, although one
puts the cylinder alternately in communication sometimes with one, sometimes
with the other of the two small vases. Upon the upper plate two thermometers
are fixed and are so arranged that when the cylinder of the instrument is upon one
of the small vases, the basin of one of the thermometers communicates with one of
the small vases and that of the other thermometer with the other small vase.
The instrument has safety tubes also and. is so arranged that one can place an
alcohol lamp under each of the vases in order to examine the influence of heat
upon the manifestations of the hygroscopic property of the substance which is
being experimented upon. The instrument rests upon a triangle supported by
three levelling screws (vis calantes) by whose aid as well as by a level in T, fixed
upon the superior turn plate, and another round level fixed upon the cover of the
cylinder, one can so regulate the position of the instrument that it shall always be
plumb. By means of this instrument one can divide the different kinds of organic
substances into " Hygrotropics" and "Non-hygrotropics." One can also examine
different kinds of organic substances from a hygroscopic point of view, and study,
from this point of view, the modifications experienced by the different hygroscopic
animal substances in a pathologic condition. In another typo of this instrument
the cylinder is fixed upon a small vase divided by a vertical midrif into two
compartments (one of which contains chloride of calcium and the other water)
having no communication with each other and each one of which may be put in
communication, by means of a cock, with the cavity of the cylinder. In another
type of the same instrument I make use of the following arrangement to remove
the moisture from the cavity of the cylinder and also to introduce moisture into it:
the cavity of the cylinder communicates by an india-rubber tube (having a flask of
india-rubber furnished with two valves, one of which opens and the other shuts
when the flask is compressed and when it is relaxed the contrary movement of the
valves is produced) with one of the mouths of a small vase containing water and
by another india-rubber tube with the other mouth of the same vase; the cylinder
communicates also by means of an india rubber tube (having a flask of india-rubber
equally supplied with two valves disposed like those of the other flask) with one
of the two mouths of a second small vase containing chloride of calcium (or con-
centrated sulphuric acid) and by another india-rubber tube with the other mouth.
of the same vase. Thus by alternatoly compressing and relaxing the first flask
(while the communication is interrupted between the cylinder and the other vase

page_text: Each
by means of two cocks) the moisture is introduced into the cavity of the cylinder
and by alternately compressing and relaxing the other flask (while the communi-
cation of the cylinder with the other small vase is interrupted by means of two
cocks) the moisture is removed from the cavity of the cylinder. With one of these
instruments one can also study the influence of the vapors of different volatile
substances upon the substance with which the helix is coated; 3°. When it is
desired to study the influence of moisture and of dryness upon the manifestations
of the contractility of organs (for example, upon the number of heart-beats, upon
the rapidity of the movements of the cilia of the ciliated epithelium, upon the
intensity of the peristaltic movements of the intestines and of the stomach),
I arrange the instrument which is to serve for this purpose in the following
manner: a) For the heart: a round turn-plate, provided with two openings each
of which has a glass cylinder fixed vertically, is placed upon a second round fixed
plate provided with two openings; under one of the last is serowed a sinall vase
containing chloride of calcium (or concentrated sulphuric acid) and under the other
another small vase containing water. A screw and a spring force the superior
plate to press with a certain force against the inferior or fixed plate.
cylinder contains a heterhygroscopic spring indicating the degree of moisture and
is provided at its superior opening with a cover (which can be easily removed)
bearing a thermometer. In introducing into each cylinder by its superior opening
a heart (for example, that of a frog, or of a little bird) suspended in the middle of
the cylinder, and in putting each cylinder in communication, by means of the
turning plate, now with one, now with another of the two vasos and in counting the
heart-beats made in moisture as well as in dryness, one thus sees the considerable
influenco which these two physical conditions exercise upon the number of heart-
bents and one determines the relation of this number with the degree of moisture.
The thermometers serve to show that this influence does not come from thermo-
metric variations; b) For the ciliated epithelium: The same arrangement as for
the heart, with this differenco, that each cylinder carries laterally an adjusting
screw provided in its extremity which is found in the interior of the cylinder with
a vertical plate of india-rubber, or of cork, upon which is exposed the membrane
with the ciliated epithelium. In the axis of the cylinder is found a small and
very light vertical cylinder of gutta-percha arranged so as to balance freely and,
consequently, to follow freely the expansion and contraction of the cilia. The
axis of this small cylinder bears a horizontal index, which is put into circular
motion (with the small cylindor) by the movements of the cilia of the ciliated
epithelium (which one puts into convenient contact with the small cylinder by
turning the adjusting screw) and indicates also the rapidity of the movement of
the ciliated epithelium in moisture and in dryness upon a divided circle which the
glass cylinder bears in its circumference.
C) For the peristaltic movements of the intestines: The same arrangement is
required as that required for the ciliated epithelium. The part of the intestines to
be examined is rolled around the plate of the adjusting screw in such a way as to
come sufficiently in contact with the small turning cylinder. When the three
instruments above described are designed for the observation of the influence of
moisture and of dryness upon a simple organ, and not simultaneously and com-
paratively upon two organs, the turn-plate then carries a simple glass cylinder
in place of two. When one wishes to study the influence of heat in different
degrees of moisture upon the manifestations of the contractility of the organs, each
of the last described three instruments (a, b, c) is disposed in the following manner.
A glass cylinder is fixed upon a single vase containing chloride of calcium and
having two valves one opening without from within and the other within from
without; another glass cylinder is fixed upon another little vaso containing water
and having two valves, similar to those of the first vase. The cylinders are
arranged as described under a, b, c. One can thus raise or lower the temperature
in each of the two vases without the temperature of one being communicated to
the other.

page_text: When it is proposed to combine an instrument of one or more heterhygroscopic
organs with an apparatus for projection, the parts of the instrument through which
light should be allowed to pass must be of glass.
When the hygrometer is to be employed for the observation of the hygrometric
state of the surrounding air, the heterhygroscopic spring is not shut up in a close
cavity, but it is arranged in such a manner as to be exposed to the action of the
open air. One of the types of hygrometers with heterbygroscopic springs not shut
up in a close cavity is represented by Figure 2. The heterhygroscopic spring is of
india-rubber; it has the form of a helix, A B. The convex face of the latter is
coated with any hygroscopic substance whatever, for example, with a solution of
cascine. The helix is suspended by one of its extremities to the superior extremity
of a rod, C D, fixed vertically and carrying a thermometer, E F.
To the inferior extremity of the helix is attached the index, G, whose axis, H, is
fixed upon a little cross-bar I. The hygrometric scale, J, is found in the appropriate
part of the instrument.
The other different arrangements which I give to the hygrometers of this system
are the following: 1°. When the non-hygroscopic substance of the spring is sufficiently
clastic (as, for example, steel, silver, and any other clastic metal), I form of this
substance a ribbon of a proper thickness (for example, one of 180 of a millimeter)
and width (for example, of a millimeter) and I roll it in the form of a helix of
small diameter (for example, of 4 millimeters). One of the faces of the helix (for
example, its convex face) is coated with a hygroscopic substance (for example, with
a solution of cascine); the helix is fastened to a fixed point either by its superior
extremity (when it carries the index at its inferior extremity), or by its inferior
extremity (when it carries the index at its superior extremity). A fixed rod
occupies, in these two arrangements, the axis of the helix; 2°. When the heter-
hygroscopic spring having the form of the segment of a circle and its hygroscopic
substance is sufficiently elastic (as, for example, a blade of ivory, of whalebone, of
shell, of horn, of the substance which forms the quills of feathers, of wood),
I arrange it, whether it is alone, or united with another segment of a circle, in such
a way that when the moisture increases, one part of the spring (or one of the two
springs) expands and the other contracts, and when the moisture diminishes, the
contrary effect takes place. I obtain this result by different arrangements based
upon the same principles as the following arrangements a) The spring is fastened
by its middle to a fixed point; one of the faces (for example, the convex face) of
one of the halves and the opposite face (for example, the concave face) of the other
half are rendered non-hygroscopic by any means whatever (for example, being coated
with an elastic and non-hygroscopic substance such as a varnish, a dissolution of
india-rubber, a siccative oil, or being covered with a thin sheet of metal or with a sheet
of the same hygroscopic substance of the same form and tho same elastic capacity as
the rest of the spring and both of whose faces (the one exposed to the air and the
ono applied to the spring have been coated with an elastic and non-hygroscopic
substance); a very fine chain (or thread), fitly rolled around a small pulley which
is found in the centre of the half circle formed by the spring, is attached by one of
its ends to one of the extremities of the spring, and by its other end to the other
extremity of the spring. Thus, when the moisture acts upon the spring, one of the
branches of the latter tends to flatten and make the little pulley and the index
attached to its axis turn towards the point of extreme moisture, whilst the other
branch bends more, letting the part of the fine chain attached at its extremity
relax and allowing the other branch to turn the small pulley freely; dryness
produces the contrary effect; b) One of those springs is fastened by one of its
extremities to a fixed point; another spring of the same form is equally fastened to
a fixed point (by its extremity which is opposed to the fixed extremity of the first
spring) in such a way as to form of the two springs a circle; one of the faces (for
example, the convex face) of the first spring and the opposite face (for example, the
concave face) of the second are rendered non hygroscopic after the manner indicated
above (a); a small pulloy which is found in the centre of the circle carries, fitlý

page_text: rolled up, a very fine chain (or a thread) one of whose ends is attached to the free
extremity of the first of the two springs and the other end to the free extremity of
the other spring. In the same arrangements, the two springs of which the opposite
faces (for example, the convex face of one and the concave face of the other) are
rendered non hygroscopic, are fastened to fixed points by their analogous (not by
their opposed) extremities which are thus side by side of each other, and the ends
of the fine chain (or thread) are fastened to analogous free extremities (which are
side by side of each other) of the springs; C) The two heterhygroscopic springs are
fastened, ench by one of its extremities, to a fixed point in such a manner as to
make with the two springs a double segment of a circle; the two springs aro
prepared and are put into communication with a small pulley (which is found in
the centre of the segment of the circle) in the same manner as in the preceding
arrangement. In each of the three. arrangements described above I employ also
two very fine chains (instead of one) properly attached to the pulley and to the
free extremity of the spring (or springs); d) the heterhygroscopic spring (one of
whose faces is rendered non hygroscopic in the manner exposed under a) is disposed
in the same manner as the barometric spring in the form of the segment of a circle
of the metallic barometer of Bourdon; e) Two heterhygroscopic springs each of
which has the form of segment of a circle are fastened together by their extremities
in such a way as to form an ellipse; one of the faces (for example, the convex face)
of one of these springs and the opposite face (for example, the concave face) of the
other are rendered non hygroscopic after the manner indicated above (under a) one
of the springs is fastened by its middle to a fixed point. The hygrometric variations
produce variations in the depression of the two springs and these movements are
transmitted to the hygrometric index by the middle of the superior (or free) spring
in the same way as in the metallic barometers with barometric springs of box form;
^ I fasten the spring by one of its extremities to a fixed point and I attach to its
free extremity one of the ends of a thread to the other end of which is attached a
counterpoise; the thread is rolled around a small pulley (which is found in the
centre of the circle whose segment is formed by the spring) to the axis of which
the index is attached. In these 6 arrangements of the heterhygroscopic spring the
last works best, if one renders non hygroscopic, not only the faces indicated above,
but also the faces which are formed by its thickness.
When the heterhygroscopic spring is of such proportions that its index makes the
tour of the dial several times in order to go from the point of extreme dryness to
the point of extreme moisture, I then employ one of the following means to
indicate the number of turns: 1° When the spring has the form of a helix and is
fixed vertically, I attach an index to its free extremity and another to one of its
spires which are near its fixed extremity; the second index indicates the number of
turns which the first makes upon the dial; 2° I combine a small heterhygroscopic
spring with the large spring; the index which is in communication with the first
points out the number of turns made by the one which is in communication with
the second.
As temperature exercises a direct influence, although small, upon some matters
and some forms of heterhygroscopic springs (for example, that of an india-rubber
helix or a metal helix), I employ to neutralise this influence one of the following
systems of compensation: 1°°I form the helix in such a way that the spires of one
part of the helix shall have a direction opposed to the spires of the other part of
the helix; 2° I fasten one of the extremities of a helix (after having coated with a
hygroscopic substance one of its faces, for example, its convex face) to a fixed point
and one of the extremities of another helix (after having coated with a hygroscopic
substance the face which is opposed to the hygroscopic face of the first helix, for
example, the concave face), of the same elastic force and having the same direction
of its spires, to another fixed point in such a way that the two helices form a
vertical helix. The index is put into proper relation with the inferior extremity
of the superior helix and with the superior extremity of the inferior helix.
I employ also a simple belix in place of two, so disposed as to give the same

page_text: result. When the spring is without compensation, I note upon a table attached to
the instrument the report of the different thermometric degrees with the deviation
which the index of the spring experiences through the action of caloric before the
application to the latter of the hygroscopic substance.
To protect the heterhygroscopic spring against dust, when it is exposed to the
open air, I set it up in a cavity so disposed that the air can freely enter, while dust
is prevented from entering. For example, when the spring is of the form of a helix
and is vertically disposed, I set it up in a glass-tube open above and below, to the
superior extremity of which a small cover is fixed, whose diameter is larger than
that of the tube.
I employ in the preparation of heterhygroscopic springs as hygroscopic substance
all substances which I recognise, by the following means, as possessing the property
of attracting moisture and of drying gradually: I coat with the substance to be
examined one of the faces (for example, the convex face) of an elastic helix (for
example, of india-rubber) vertically fastened by one of its extremities to a fixed
point and bearing an index in its inferior (or free) extremity. I expose the helix
alternately to moisture and dryness and I thus recognise whether the substance
examined is hygroscopic or not.
When the hygroscopic substance becomes brittle in extreme dryness (as, for
example, starch, caseine &), to suppress this inconvenience I add to the hygro-
scopic substance a very small quantity (sufficient to prevent the hygroscopic
substance from becoming brittle when applied to a metallic helix and exposed to
extreme dryness) of a substance having the property of not drying up, such as
glycerine, molasses and several other substances.
I give to the heterhygroscopic spring the form suited to each arrangement of the
instrument, for example, that of a helix, or of a segment of a circle, or of an ellipse,
or of a spiral, either conic or plain. I give to its free extremity, to the axis around
which it turns when it has the form of a helix, to the dial and, in general, to the
entire instrument the arrangement essential to the perfect working of the latter.
When the spring has the form of a helix, I fix it vertically or horizontally (with
a dial either vertical or borizontal). The free extremity of the helix is provided or
not with a small ring open on both sides, or provided on one side with a bottom
having in its centre a small hole in which enters the metallic axis around which the
helix turns. When the hygrometer is destined to remain always in the same place
(for example, in an observatory) and its heterhygroscopic spring has the form of a
helix, this last can freely turn and not be provided with a metallic axis. When
the spring is of the form of a helix and is disposed vertically, the instrument can
be arranged to be suspended and to assume freely a vertical position, or it can rest
upon a triangle supported by three levelling screws and be provided with a level.
When the non-hygroscopic substance with which I coat one side of the heter-
hygroscopic spring is alterable by the action of the air (as, for example, varnish,
siccative oils), I recover the face of the spring which is coated with this substance
with a substance which is not affected by the action of the air (as, for example, gold
in the form of gold foil or impalpable powder).
I provide a maximum and a minimum arrangement for some of the hygrometers
with heterbygroscopic springs in a manner suited to each type of the instrument.
For example, when the dial is horizontal, I provide the latter with a border curved
upward and I hang upon each side of the index a very light indicator; thus the
index, meeting one of the indicators in its progressive march, and the other in its
retrograde march, pushes and displaces them easily.
I combine some of the hygrometers of the system herein described with any
registering apparatus whatever which registers the hygrometric indications of the
instrument.
I combine some of the hygrometers of the system here described with a table
giving the fraction of saturation which corresponds with each degrco indicated by
the hygrometor.

page_text: The graduation of hygrometers with heterhygroscopic springs is done in the
same way as the graduation of hair-hygrometers.
One can employ the heterhygroscopic springs for the construction not only of
hygrometers, but also of any other instruments or toys in whose construction onc
or several hygroscopic organs are used, or may be used, such as the popular instru-
ments which are employed to foretel fine weather or rain.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is:
First The system (based upon the principle set forth in this Specification) of
construction of hygrometers (whatever may be the arrangement that one gives
them) and of any other instrument into whose construction one or several
hygroscopic organs are used, or may be used.
Second-The combination of any elastic and nonhygroscopic (or slightly hygro-
scopic) substance whatever with a substance (simple or compound) hygroscopic (or
more hygroscopic than the former) and the preparation, by this combination, of
heterhygroscopic springs, whatever may be the use to which they are destined,
their dimension, their form, their arrangement, and that part of them having the
property of attracting moisture.
Third-The different arrangements indicated in the present Specification of the
heterbygroscopic springs (and every other arrangement fulfilling the same end) for
the construction of hygrometric instruments; the arrangement for the different
physiological and medical instruments described herein.
Fourth-The different combinations here indicated of some of the hygrometers
with heterhygroscopic springs with a thermometer, with a multiplicator, with an
amplifier, with a arrangement indicating the maxima and minima, with a table
giving the fraction of saturation which corresponds to each hygrometric degree
indicated by the instrument and the relation of the deviation of the index to each
thermometric degree under the direct action of heat upon the non-hygroscopic
matter of the spring, with an apparatus for registering and with an apparatus for
the projection of light.
Fifth-The means described in this Specification by which one obtains com-
pensation for the influence which thermometric variations exercise upon the
non-hygroscopic part of some of the heterhygroscopic springs.
Sixth-The arrangement for enclosing the hygroscopic organ in a cavity
constantly closed, or provided with an opening which may be casily opened and
shut.
Seventh-The employment as hygroscopic substances, of different materials
indicated in the present Specification as proper to serve this end, as well as any
other substance in which the means of examination indicated in this Specification
reveal this property.
Eighth The means indicated in this Specification, by which one prevents any
of the hygroscopic substances from becoming brittle in extreme dryness.
Ninth The means indicated in this Specification by which one preserves from
alteration caused by the action of the air the non-hygroscopic substances with
which a part of a hetorhygroscopic spring is coated.
Tenth The different forms of heterhygroscopic springs indicated in the present
Specification.
D
JO 100A