Improvements in Apparatus for Facilitating the Delineation of the Outlines of Type Faces and other Objects.
Year: 1896

page_text: Date of Application, 21st Oct., 1896
Complete Specification Left, 21st July, 1897-Accepted, 21st Oct., 1897
Improvements in Apparatus for Facilitating the Delineation of the
Outlines of Type Faces and other Objects.
I, FRANK HARRISON PIERPONT, of Hartford, in the State of Connecticut, one
of the United States of America, but at present of Kant Strasse, 156,
Charlottenburg, Berlin, W., late of Savoy Hotel, Berlin, in the German Empire,
Engineer, do hereby declare the nature of this invention to be as follows:-
My invention relates to improvements in apparatus for facilitating the delinea-
tion of the outlines of type faces and other objects, and consists in a particular
combination of optical and mechanical devices.
It has already been proposed to utilise a microscope for the purpose of enlarging
the details of a surface previous to its delineation being attempted, and to combine
with such microscope, a camera lucida, in order that the rays of light from the
said surface and from that upon which the delineation is to be made, may meet
in the draughtsman's eye, and produce there what is practically one image as
distinguished from two separate ones. The two surfaces, above mentioned are
hereinafter referred to as original and paper respectively.
In all microscopic images, there is a certain amount of spherical aberration.
This makes itself apparent at a certain distance from the centre of the field and
increases in amount with the distance from that centre of the point under observa-
tion. Its reproduction in the delineation, is, of course, fatal to the accuracy of
the latter.
The particular object of the combination above mentioned, is to provide an
automatic check upon the amount of aberration in the delineation. It is attained,
as far as the optical part of the combination is concerned, by placing in the field
of the microscope, only a definite portion of the original, (so correspondingly
restricting the surface of the paper in the image on the retina) and by following
that with a second and like portion of the original (such second portion being the
one adjacent to the first one) and a second and like portion of the paper, being
the one likewise adjacent to the first portion thereof.
The delineation of the first portion of the original on the paper, reproduces the
aberration present in the microscopic image. Let it be assumed that the field
is square, each respective portion of the paper being square also. A maximum
degree of aberration will make itself apparent at the edges of the square on the
paper. But the next portion of the original is moved into the field only so far as
to bring that edge of it which, in the original, immediately adjoins and follows
the first portion, into the central portion of the field, that is into that part of
it where there is no aberration. The delineation of the said edge will be true
and indicate exactly the degree of aberration reproduced in the first portion of

page_text: the delineation. Thus throughout the entire process of delineation, will there be
a portion of it detecting and indicating the amount of aberration in the one
immediately preceding it and, consequently, providing for its correction.
The invention does not in any way limit me to the area of the portion of the
original admitted into the field at each adjustment of such original. That is
a matter to be decided according to circumstances. It may be remarked that,
as a consequence of the above described and novel subdivision method of dealing
with the original, as many checks may be applied, and that at equal distances
in both directions, that is on all sides of the squares, as may be desired.
The optical part of the combination consists of a microscope, an illuminator of
any suitable type, and a camera lucida. The illuminator may be either a prism
in the microscope itself between the eye piece and the objective, receiving rays
of light through an aperture in the microscope tube and deflecting them down.
upon the original; or it may be an ordinary condenser. The camera lucida is
arranged above the microscope as follows. There is a prism in the eye point of
the eye piece, so placed that its oblique face stands at an angle of 45° with the
axis of the instrument as well as with the field. This surface is silvered so as
to convert it into a mirror. A second prism is cemented to the former, the two
forming a cube. There is a small aperture in the silvering capable of passing
the rays from the microscope image to the eye. Over the paper and opposite
the mirror above described, there is supported a second and plane mirror at the
same angle and over that portion of the paper to be dealt with. This mirror is
conveniently (and preferably) supported by an arm springing from the microscope.
It is to be noted that there is no limit imposed by the invention upon the
nature of the substance upon the surface of which the delineation is made. It
may be either paper, and the delineating instrument, a pencil; or it may be any
plastic or other substance capable of being cut or carved or modelled, the delineat-
ing instrument being adapted to the nature of the said substance. The colour of
the substance cannot have any effect in diminishing the distinctness of the image
on the retina, for the reason that there is always a stronger light directed upon
the original than finds its way to such substance.
The internal construction of the microscope is modified as may be advisable in
view of rays which are not required in the eye for the purpose of delineation.
For instance, in the case of a type, the inclined shoulders and the base or upper
end of the body, are of no moment. They can be dispensed with. Only such
rays of light as fall upon the face are reflected to the eye. All those which fall
on the inclined shoulders or base above mentioned, are reflected to and absorbed
by the walls of the instrument. The completed delineation is included within
a rectangular area which accurately represents the body of the type from which
latter it had been copied, and it is so situated that its inclination to, and its
distance from, the foot line and side lines, are exactly in accordance with the
scale to which it is drawn.
The mechanical part of the combination consists of a strong base and a double
table thereupon. One of these tables is capable of a linear motion upon the
base in one direction, while the other is capable of a like linear motion upon
the one before mentioned; but at right angles therewith. The directions of these
two motions harmonise with the squareness of the field and with those of its
sides, respectively. Suitable traversing devices with automatic detents, are provided
for each table in order that each motion may be certain and definite.
The microscope is supported adjustably as to height, by the base above men-
tioned. The stage of it is fitted with a pair of slides, the counterparts of the
two tables above described, being moveable over each other in directions at right
angles with each other and therefore parallel with the respective motions of the
said tables, respectively. The said slides are likewise fitted with suitable traversing
and detent mechanisms of considerable exactness. The last mentioned mechanisms
are co-ordinated with those of the tables above described in such a way that a
unitary or single motion of one table bears the same relation to a unitary or

page_text: single motion of the respective slide, as the size of the microscopic image bears
to the size of the original. Exact correspondence between the motions respect-
ively, will result obviously in exact correspondence of dimension between original
and delineation. If an enlargement or contraction in either direction be desired,
it is effected by modifying the relation between the motions of one table and
slide in one direction and the motions of the other table and slide in the other
direction.
Dated thi 01 dose of Dentahan 1806
Improvements in Apparatus for Facilitating the Delineation of the
Outlines of Type Faces and other Objects.
I, FRANK HARRISON PIERPONT of Hartford, in the State of Connecticut, one
of the United States of America, but at present of Kant Strasse, 156,
Charlottenburg, Berlin W., late of Savoy Hotel, Berlin, in the German Empire,
Engineer, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement:-
My invention relates to improvements in apparatus for facilitating the delinea-
tion of the outlines of type faces and other objects; and consists in a particular
combination of optical and mechanical devices.
It has already been proposed to utilise a microscope for the purpose of enlarging
the details of a surface previous to its delineation being attempted, and to combine
with such microscope, a camera lucida, as in the well known drawing camera, in
order that the rays of light from the said surface and from that upon which the
delineation is to be made, may meet in the draughtsman's eye, and produce there
what is practically one image, as distinguished from two separate ones. But no
provision has yet been made for eliminating the spherical aberration which is
always present to a greater or smaller degree in a microscopic image.
aberration makes itself apparent at a certain distance from the centre of the
field and increases in amount with the distance of the point under observation from
that centre. Its reproduction in the delineation is, of course, fatal to the accuracy
of the latter.
This
The object of the particular combination above mentioned, is to provide an
automatic check upon the amount of aberration in the delineation. It is attained
as far as the optical part of the said combination is concerned, by placing in
the field of the microscope, only a definite portion of the original (so correspond-
ingly restricting the surface of the paper, or whatever is the material upon which
the delineation is to be made, in the image on the retina); and by following
that with a second and like portion of the original (such second portion being the
one adjacent to the first one in any given direction) and a second and like portion
of the paper, being the one likewise adjacent in the same direction to the first
portion thereof.
The delineation on the paper of the first portion of the original, reproduces the
aberration present in the microscopic image. Let it be assumed that the field
is square. A maximum degree of aberration will make itself apparent where the
lines of the delineation touches the edges of the enclosing square on the paper.
But the next portion of the original is moved into the field only so far as to

page_text: bring that edge of it which immediately adjoins and follows the first portion,
into the central portion of the field, that is into that part of it where there is
no aberration. The delineation of the said edge will be true and indicate exactly
the degree of aberration reproduced in the first portion of the delineation. This
portion is then corrected. Thus, throughout the entire process of delineation,
will there be a portion of it detecting and indicating the amount of aberration
in the one immediately preceding it, and, consequently, providing for its
correction.
The invention does not in any way limit me to the area of the portion of the
original admitted into the field at each adjustment of such original. That is
a matter to be decided according to circumstances. It is obvious that the more
the area of the original is divided, the more accurate will be the finished delinea-
tion, for the reason that each subsequent division brings with it, its own capacity
for checking the delineation of the preceding one. It is recommended that, the
divisions shall be equal throughout. Otherwise, a greater degree of accuracy
will obtain in one part of the delineation than in another.
In order that my invention and the means by which it is to be carried into
effect may be thoroughly understood, I will now describe it and them in detail,
referring in so doing to the accompanying figures which are to be taken as part
of this specification and read therewith, and in which like parts are markel
throughout with the same reference letter.
Figure 1 is a diagrammatic representation of the optical elements of the
improved apparatus.
Figure 2 is a front elevation of the entire apparatus.
Figure 3 is a side elevation corresponding therewith from the left.
Figure 4 is a sectional plan taken along the line 4-4 of Figure 3.
Figure 5 is a
plan corresponding with Figures 2 and 3.
The optical part of the combination consists of a microscope A, an illuminator B
of any suitable type, and a camera lucida C. The illuminator may be either a
prism in the microscope itself between the eye piece a and the objective a', receiving
rays of light through an aperture a² in the microscope tube and deflecting them
down upon the original D; or it may be an ordinary condenser. The camera
lucida is arranged above the microscope as follows. There is a prism c in the
eye-point of the eye piece a so placed that its oblique face stands at an angle
of 45° with the axis of the instrument as well as with the field. This surface
is silvered so as to convert it into a mirror. A second prism c¹ is cemented to
the former, the two forming a cube. There is a small aperture in the silvering
capable of passing the rays from the microscope image to the eye. The aperture ca
is shewn in Figure 1 as a black dot. Over the paper E and opposite the mirror
above described, there is supported a second and plane mirror at the same angle
and over that portion of the paper to be dealt with. This mirror is conveniently
(and preferably) supported by an arm springing from the eye piece a.
optical part just described constitutes what is generally known as a drawing
camera.
The
It is to be noted that there is no limit imposed by the invention upon the
nature of the substance upon the surface of which the delineation is made. It
may be either paper, the delineating instrument being a pencil; or it may be
any plastic or other substance capable of being cut or carved or modelled, the
delineating instrument being always adapted to the nature of the said substance.
The colour of the substance can not have any effect in diminishing the distinctness
of the image on the retina, for the reason that there is always a stronger light
directed upon the original than finds its way to such substance. The internal
construction of the microscope is modified as may be required in view of rays
which are not required in the eye for the purpose of delineation. For instance,
in the case of a type, the inclined shoulders d and the top of the body d', are
of no moment. They may be disregarded. Only such rays of light as fall upon
the face are reflected to the eye. All those which fall upon the inclined shoulders

page_text: or upon the top above mentioned, are reflected to and absorbed by the walls
of the instrument, they being properly constructed for the purpose. The com-
pleted delineation is included within a rectangular area which accurately
represents the top of the body d' of the type from which latter it had been copied,
and it is so situated that its inclination to, and its distance from, the foot line
and side lines, are exactly in accordance with the scale to which it is drawn.
The mechanical part of the combination consists principally of a firm base F,
a pair of traversing tables G, H; and a bracket I springing from the said base
and supporting the microscope at a suitable height above the said base and tables;
and a pair of traversing slides J, K.
The bottom table G is rather smaller than the top of the base F and fits down
upon it. It is capable of a reciprocating linear motion upon the said base in
one direction, while the top fable H is capable of a similar motion upon it-the
bottom one G-but at right angles with that of the latter upon the base F. Both
these motions are provided for in the well known way by means of ridges and
grooves, each table being fitted with a releaseable detent. g, g are a pair of
ridges fast upon the bottom of the table G close to the respective front and rear
edges and engaging in corresponding grooves g¹, g¹, which extend the full length
of the base F. g is a spring-actuated detent presenting a push piece beyond
the front of the base F. It works in a suitable recess standing at right angles
with the motion of the table G. 93, 93 are a series of equal and equidistant
notches in the inner face of the respective ridge g; and in each of them the
detent ga engages, when the two are opposite each other, thereby locking the
table G in the corresponding position.
The top table H is smaller than the bottom table G and fits down upon it.
It has a groove h in its under side parallel with the direction of its intended
motion. This groove fits over a ridge upon and fast to the table G. h¹ is an
automatic detent; and h³, ha a series of equal and equidistant notches in the
ridge g, for locking the table H in any position corresponding with that of one
of the said notches, in the same way as the detent ga locks the table G. The
notches h are at the same distance apart as the notches g. The sheet of paper E
is stretched across the table H and held down there upon by clipping strips h, h4,
along the front and back edges of the said table.
The bracket I is detachably held to the base F by a clamping screw and nut i.
The screw passes through a vertical slot 2, instead of a hole of its own size, in
the vertical portion of the bracket, and that portion fits in a vertical
23
groove
in the end of the base F; in order that the height of the microscope above the
table H may be easily adjusted. For exactness of adjustment, the microscope is
fitted with the usual rack device.
The stage of the microscope A consists of a pair of slides J, K. These are,
respectively, the counterparts of the tables G and H above described. The slide J
is inoveable upon the frame of the stage in the same way and direction as the
table G upon the base F, and the slide K upon the slide J in the same way and
direction as the table H upon the table G. They are, respectively, fitted with
traversing and detent mechanisms j, k. These latter must be of considered exact-
ness. They are co-ordinated with the series of notches of the tables G and H,
respectively, in such a way that a unitary or single motion of one table (i.e., from
one notch to the next in the respective series), bears the same relation to a unitary
or single motion of the respective slide, J or K as the case may be, as the size
of the microscope image bears to the size of the original. Suitable devices of
any convenient kind are fitted to the pair of slides for holding the type D, or
whatever the original may be, in position to the top slide K.
Exact correspondence between the motion of the slides J, K, and the tables G, H,
respectively, will result in exact correspondence of dimension between original
and delineation.
There is a constant relation between the motions of the tables G, H, and
slides J, K, on the one hand; and the dimensions of the projected image on the

page_text: paper in view of those of the original, on the other hand. Thus, if the linear
dimensions of the delineation are to be six times those of the original, the motions
of the table G, H, must at each adjustment, be six times those of the slides J, K,
respectively.
When the object to be delineated is rectilinear with lines running parallel to
the movement of the tables and without fine divisions capable of being embraced
in one field of the microscope, either dimension of the projected image may be
increased or decreased by a corresponding increase or decrease of the motion of
the respective table, G or H as the case may be, in view of the motion of the
respective slide J and K.
The width only of the projected image may be increased or decreased, by alter-
ing accordingly the angle of 45° described above as that which the mirror c
normally stands.
Further, any projected image may be either increased or decreased by moving
the camera lucida further from or nearer to the paper.
Lis an adjustable and detachable obscurer to save the observer the trouble of
closing one eye.
The figures indicate that the type D is a "G," and that it is being delineated
by fourths of its area at a time. The first adjustment of the said type under the
microscope, puts, say, the top left hand corner of the type face in the centre
of the field. The corresponding part of the first quarter e¹ of the delineation will
be practically accurate, while the aberration will make itself increasingly apparent
in the direction of the right and bottom edges of the said quarter. The type is
next moved to the left, till the top left hand corner of the second quarter in the
centre of the field, the tables G and H being moved accordingly. The projection
of the second quarter of the type, checks the aberration in the first quarter e
of the delineation, and shews the amount of it, so that it can be removed by
erasing as much of the delineation as is inaccurate, and redrawing to the projection
of the top left hand corner of the second quarter. The second quarter of the
delineation will be practically accurate where it joins the first quarter e', and so
on with the third and fourth quarter e³, e. The full and dotted lines of the
delineation indicate that the first three quarters have been delineated and corrected
and that the projection of the fourth quarter of the type has just been effected.
In the case of the "G," the top or last edge of the fourth quarter of the delineation
does not touch the bottom edge of the first quarter. These last mentioned edges
may be corrected by bringing the corresponding parts of the type D successively
into the centre of the field and adjusting the two tables G and H accordingly. The
capacity of the pair of slides J and K and of the pair of tables G and H for
mutually corresponding adjustments, may be carried as far in the direction of
fineness, as the nature of the objects to be delineated, may require. The above
mentioned capacity leads up to another, viz.:-the capacity for dividing and
sub-dividing the field, with the original in it, as well as the paper co-ordinately
therewith. It is this latter capacity which is the distinguishing feature of the
present invention and the source of the check upon aberration which that invention
provides. The drawing cameras hitherto known-have not possessed it. They
have only one field and can only give one projection.
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:-
1. The combination with a microscope and camera lucida, of adjustable
mechanism for co-ordinately dividing the field of the former and the surface upon
which the latter projects, the image which it receives, for the purpose of eliminating
spherical aberration from the projected image.
2. The combination with a microscope and camera lucida, of a pair of slides
forming practically the microscope stage, and a pair of tables standing under the
mirror of the comera lucida, the said slides capable of movement independently

page_text: of each other in parallel planes, and the said slides likewise capable of movement
independently of each other in parallel planes, for the purpose of dividing up
the microscope field and the paper or its equivalent.
Dated this 21st day of July 1897.
PHILLIPS & LEIGH,
No. 22 Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Applicant.