CERTAIN METHODS OF CONSTRUCTING AND MY SEVERAL IMPROVEMENTS IN THE CONSTRUCTION OF HYDROMETERS FOR ASCER- TAINING THE STRENGTH OF SPIRITUOUS LIQUORS, AND MY INVENTION AND ADOPTION OF A SLIDING RULE OF CORRECTION FOR TEMPERATURE TO THE HYDROMETER AND VARIOUS IMPROVEMENTS THEREOF
Year: 1803

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
ATKINS, of Fenchurch Street, in the City of London, Mathematical Instrument
Maker, send greeting.
WHEREAS His most Excellent Majesty King George the Third did,
by His Letters Patent under the Great Scal of His United Kingdom of
Great Britain and Ireland, bearing date at Westminster, the Thirty-first
day of October, in the forty-fourth year of His reign, give and grant unto
me, the said. Robert Atkins, my executors, administrators, and assigns His
especial licence, that I, the said Robert Atkins, my executors, administrators,
and assigns, during the term of years therein mentioned, should and lawfully
might make, use, exercise, and vend, within England, Wales, and the Town
of Berwick-upon-Tweed, my Invention of "CERTAIN METHODS OF CONSTRUCTING
AND MY SEVERAL IMPROVEMENTS IN THE CONSTRUCTION OF HYDROMETERS FOR ASCER-
TAINING THE STRENGTH OF SPIRITUOUS LIQUORS, AND MY INVENTION AND ADOPTION
OF A SLIDING RULE OF CORRECTION FOR TEMPERATURE TO THE HYDROMETER
AND VARIOUS IMPROVEMENTS THEREOF;" in which said Letters Patent there is
contained a proviso, obliging me, the said Robert Atkins, by an instrument in
writing under my hand and seal, to cause a particular description of the nature
of my said Invention, and in what manner the same is to be performed, to be
inrolled in His Majesty's High Court of Chancery within six calendar months
after the date of the said recited Letters Patent, as in and, by the same
(relation being thereunto had) may more fully, and at large appear.
NOW KNOW YE, that I, the said Robert Atkins, in compliance with the
said proviso in the said Letters Patent, do hereby declare that my said

page_text: Inventions and improvements in the hydrometer and sliding rule of correction
for temperature are described and explained as follows:-
The hydrometer, with the following improvements adapted to it, may be
made of any dimensions, and of any convenient form, consisting of a hollow
metallic bulb with a polygonal stem, consisting of three sides, which are
graduated with divisions that indicate specific gravities or degrees of strength
of spirituous liquors, over and under proof, and it has a shank proceeding from
the opposite end of the bulb to which weights are to be affixed, as is usual
in other hydrometers; on one of the faces of this polygonal stem, which I
enamel, gild, silver, or varnish, I engrave or paint a series of divisions
representing per centages or degrees of strength over proof, expressed in
commercial terms, the line which indicates proof being at the lower end of
the stem near the bulb marked "P." or "Pr." and the per centages over
proof are marked in successive graduations as high as the length of the stem
will admit. Another face of the stem which may be enamelled or coloured
differently from the last mentioned, has a series of divisions on it expressing
per centages or degrees of strength under proof. The proof mark being at
the superior extremity of the stem, and the graduation proceeding in an
inverse direction to that of the over-proof side. The rotation may also be
expressed in Roman characters on this side or vice versa. The degree of
strength of any compound of water and alcohol may be expressed in various
ways, the mode above-mentioned is that which has been in common use of
gallons to the hundred over or under proof," which is an arbitrary term
adopted from custom, and consequently well known, I have, however, invented
another mode of expression, which may enable the excise officer and merchant
to ascertain with greater facility the quantity of proof spirit which several
different quantities of an over proof spirit may contain, or, in other words, it
will facilitate the operation of casting up the over proofs on any given
quantity according to this method the degrees of strength are expressed in
ten per cents. over or under proof, and the fractional parts of ten halves and
quarters, viz, ten per cent. over or under proof, ten and one quarter, ten and
one half, and so on with twenty. This being understood, the following notation
will be easily comprehended, the letters O or U imeaning over or under proof:-
%%%%/10, °/10, °/10, °/104, °/20°/20°/201, /20, 0/30, °/30, &c.
""""/10, "/10, "/10, "/10, "/20, "/20, "/20, "/201, "/30, "/301, &c.,
or instead of 10, 20, 30, &c. it may be expressed more simply by units 1,
2, 3, &c. In order, to adapt the instrument constructed in this way to the
various degrees of heat at which spirituous liquors are found to be in the
ordinary states of the atmosphere, I adjust a series of thermometer weights
6

page_text: o various temperatures between 80 degrees and 80 of Fahranheit's scale,
which I make of different figures that they may be more easily distin-
guished from each other, three of them triangularly, three square, three
pentagonal, and three circular, and three more of some other figure, if necessary,
each set I number 1, 2, 3. The form and number of each of these weights
I engrave on the thermometer scale, opposito to the temperature to which
each is respectively adjusted; against 80 degrees on the thermometer, or
some other degree, for instance, I engrave or mark the character and number
of the lightest thermometer; weights, thus 80-A1, the next below it is
represented thus Az, &c.; so that the character and number which the
quicksilver in the thermometer may stand opposite to will shew the character
and number of the weight to be applied in order to discover the strength of
any sample of spirituous liquor under examination. These weights may be
either applied to a wire at the top of the stem, or pass over it and rest on the
bulb, or be adapted to the lower end of the shank, or in whatever way the
artist may chuse to adopt.
If the hydrometer be immersed in any spirituous liquor which is over proof
and loaded with the weight that is indicated by its temperature, the divisions
on the side of the stem, which I mark O. P. or over proofs, with the proof
mark at the bottom of it will indicate the various degrees of strength of such
kind of spirits, but if they are under proof, a small weight, which I mark U. P.
or under proof, must be applied to the instrument, which may be made either
to screw on, or to slide on to the bottom of the shank, in which case the under-
proof side of the stem with the proof mark at the top of it will indicate all
such degrees of strength. This instrument, therefore, with one weight for
under proofs and the thermometer weights, as already described, will indicato
immediately on inspection the degree of strength of any spirituous liquor in
which it may be immersed, that is met with in the market, and each division
or per centage is perfectly distinct and legible; for the purpose, however,
of rendering this instrument as complete as possible for the distiller and
1
rectifier, as well as for the merchant and the officers of the revenue.
graduate the third side or face of the stem with a series of equal parts,
which may be marked either numerically or alphabetically, and which refer
to the sliding rule for correction of temperature; these graduations may
consist of any number that can be distinctly seen. I likewise adopt three
weights to this face of the stem and the sliding rule and mark them in the
order of their value "Rule 1," "Rule 2," "Rule 3," and farther distinguish
them from those which refer to the other sides of the stem by making them
of different geometrical figures.

page_text: The sliding rule, next to be described, is similar to that invented by the late
Matthew Quin, and which is well known. It is constructed to indicate the
relative value or strength of any sample of spirituous liquor at some standard
temperature whatever it may be at the time of examination. This standard
temperature may be any degree which the hydrometer maker may chuse to
adopt, until it shall be settled by authority of Parliament; the specific gravity
of water and that of proof spirit being assumed. The series of divisions on
the sliding rule to which the hydrometer refers when it is used without any
of the detached weights being applied to it, and which series of divisions are
equal in number to those on the face of the stem last described, I mark
"without weights," by which I mean that if the instrument on being immersed
in any spirituous liquor should subside in it so far as that its surface will cut
some division on the stem, the reference to the rule for ascertaining the
specific gravity and strength must be to the series of divisions on it marked
"without weights;" for the inferior degrees of strength it is necessary to load
the instrument with one of the rule weights, which I mark "Rule 1," or
"2," or "3," the description and number of which I mark on the rule
opposite to the series of divisions to which each respectively refers. These
serics I distinguish from each other on the rule by lines, perpendicular to the
London of th

page_text: dimensions throughout their whole length, may be easily moved or set to
any part of the rule; but when it is to be folded up they must be returned
to their proper situations on each side of the joint. By this contrivance
I unite the advantages of large and perspicuous graduations with those of
portability. The instrument and sliding rule, as above described, combines
every advantage which other hydrometers are supposed individually to possess;
and by means of the various Inventions and improvements that I have adapted
to them, and explained in this Specification, their utility to the public will, it
is presumed, be rendered sufficiently manifest to every capacity, but more
particularly to those who are in the habit of using such instruments daily,
and who are consequently most competent to decide on their real merits or
demerits.
In witness whereof, I, the said Robert Atkins, have hereunto set my
hand and seal, this Thirtieth day of April, in the year of our Lord