Year: 1899

page_text: Date of Application, 26th Sept., 1899
Complete Specification Left, 12th June, 1900-Accepted, 21st July, 1900-
I, FRANCIS CHARLES FARMAR, of 38, Thorndale Road, Waterloo, near Liverpool,
in the County of Lancashire, Officer of Customs, do hereby declare the nature
of this invention to be as follows:-
My invention relates to an improved slide-rule for computing and calculating
purposes.
This invention is essentially characterised, (1) by the employment of a single
radius of logarithmical divisions in operation with a line of segments. broken into
two equal parts; (2) by the employment of another single radius of logarithmical
divisions in operation with its own counterpart; and (3) by the introduction of
two sub-divided section enlargements of the same, as an auxiliary help.
The rule in question, which may be made in wood, ivory, or other suitable
material, consists preferably of two narrow flat pieces of boxwood, kept at an
even distance apart by brasses at each end, to allow of another piece, a trifle
longer, sliding freely between them on the tongue and groove principle.
The length of the rule depends upon the length of the radius chosen. I prefer,
however, a 20-inch radius, allowing a rule of 22 inches in length, with wide
and clear sub-divisions.
The computing rules hitherto in use are constructed on the double-radius prin-
ciple, which, in my opinion, produces an unnecessary repetition of figures, and an
expenditure of space which might be more profitably employed in widening the
subdivisions, and rendering them legible, and at the same time complete.
These objections I here seek to remedy by the following means:-Utilising
both sides of the rule, one side is occupied thus: I place on the slide Fig. 1 (a),
Fig. 3 () a single radius of logarithmical divisions in upper and lower position.
On the upper stock Fig. 1 (b), Fig. 3 (h) I place the commencing half of a line
of segments for lying casks; and on the lower stock Fig. 1 (c), Fig. 3 (j) the
terminating half of the same line; the point of severance occurring at seg-
ment "37." The four extremities of this broken segment line Fig. 1 (b), Fig. 3 (h),
Fig. 1 (c), Fig. 3 (j) are distinguished on the rule by the letters A, B, C, D, to
indicate the four definite bung-setting positions.
The other side of the rule is occupied thus: I divide the slide into two parts
by a line extending the whole distance of its length. On the upper part Fig. 2 (d),
Fig. 4 () I place a single radius of logarithmical divisions. On the upper
stock Fig. 2 (e) Fig. 4 (?) I place another single radius of logarithmical divi-
sions. These operating together perform mechanically all proportional, percen-
tage, and multiplying calculations-it being understood that both extremities of
the upper line become setting-points. On the lower part of the slide Fig. 2 (f),
Fig. 4 (m) I place a 10-fold enlargement of a section of the before-mentioned
logarithmical radius, extending from 130 to 170 inclusive, and decimally sub-
divided. On the lower stock Fig. 2 (g), Fig. 4 (n) I place a similar 10-fold
enlargement, extending from 100 to 127, also decimally subdivided.
operating together facilitate the rapid multiplication of numbers lying between
their respective limits.
Dated this Twenty-third day of September 1800
These
FRANCIS C. FARMAR,
Applicant,

page_text: I, FRANCIS CHARLES FARMAR, of 38, Thorndale Road, Waterloo, near Liverpool,
in the County of Lancashire, Officer of Customs, 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:-
1. My invention relates to an improved slide-rule for computing and calculat-.
ing purposes.
2. This invention is essentially characterised: (1) by the employment of a
single radius of logarithmical divisions, in operation with a line of segments
broken into two equal parts; (2) by the employment of another single radius of
logarithmical divisions in operation with its own counterpart; and (3) by the
introduction of two subdivided section-enlargements of the same, as an auxiliary
help.
3. The rule in question, which may be made in wood, ivory, or other suitable
material, consists preferably of two narrow flat pieces of boxwood, kept at an
even distance apart by brasses at each end, to allow of another piece, a trifle
longer, sliding freely between them on the tongue and groove principle.
4. The length of the rule depends upon the length of the radius chosen, and
will vary according to the degree of clearness and perfection required.
5. The logarithmical slide-rules hitherto in use for similar computing purposes,
are constructed on the double-radius principle, which, in my opinion, produces
an unnecessary repetition of figures, and an expenditure of space which might be
more profitably utilised in widening and completing the subdivisions.
6. It is not essential that both sides of the rule should be marked. All the
figuring may, if desired, be placed on the one side but this would necessitate
the further widening of the rule, and the introduction of a second slide, which
would be likely to prove inconvenient in practical use.
7. Therefore, preferably utilising both sides of the rule, one side is occupied
thus:-
8. I place on the slide (Fig. 1b) a single radius of logarithmical divisions, in
upper and lower position. On the upper stock, I place the commencing half of
a line of segments, which may be either lying segments, as shown separately in
Fig. 1(a), or standing segments, as shown conjointly in Fig. 3 (a)-the breakage
of the segment line constituting the fundamental principle of the invention. And
on the lower stock-Fig. 1 (c), or Fig. 3 (c), as the case may be-I place the
terminating half or complement of the same line or lines. The point of breakage
or severance will occur, in the case of lying segments, at 37 (Fig. 1d), and in the
case of standing segments, at 84 (Fig. 3). The four extremities of such broken
segment line or lines are distinguished on the rule by the letters A, B, C, D, to
indicate the four definite bung or length-setting positions.
9. The other side of the rule I occupy thus;-
10. I divide the slide into two parts by a line extending the whole distance of
its length. On the upper part (Fig. 2b) I place a single radius of logarithmical
divisions and on the upper stock (Fig. 2) I place another single radius of
logarithmical divisions--the one being a counterpart of the other. These operating
together perform mechanically all proportional, percentage, and multiplying cal-
culations it being understood that both extremities of the upper line now
become, and are hereby constituted, setting-points. On the lower part of the
slide, I place a ten-fold or other suitable enlargement of a section of the before-
mentioned logarithmical radius. Fig. 2 (c) illustrates such an enlarged section,
extending from 130 to 170 inclusive, and subdivided. On the lower stock, I place

page_text: a ten-fold or other suitable enlargement of another section of the same logarith-
mical radius. Fig. 2 (d) illustrates such an enlarged section, extending from 100
to 127 inclusive, and subdivided. These operating together facilitate the rapid
multiplication of numbers lying between their respective limits. Similarly, any
other sections may be taken and enlarged within the limits of the rule.
11. The main object intended to be served by my invention, is to provide a
portable slide-rule, capable (1) of computing with more clearness and exactitude
the ullage-quantities in lying or standing casks, whose full contents have been
already ascertained; and (2) of calculating with greater rapidity and certainty
any ordinary proof-quantity from any given ullage and strength.
12. The method of working this rule is as follows, from which it will be seen
that there is introduced a new principle in slide-setting, and in the general mode
of rule manipulation.
13. The four extremities of the broken segment line or lines are, as already
stated, distinguished on the rule by the letters A, B, C, D, to indicate the four
definite bung or length-setting positions. [Vide Figs. 1 and 3]. Thus:-
14. Setting the bung-dimension, or length-dimension (according as the cask is
lying or standing), to A, we get the segments for vacuities or ullages under an inch.
15. Setting the bung or length to B, we get the segments for vacuities or
ullages over an inch-up to th of the bung or length.
16. Setting the bung or length to C, we get the segments for vacuities or
ullages over ot of the bung or length-up to 10 inches.
17. Setting the bung or length to D, we get the segments for vacuities or
ullages over 10 inches-up to the extreme limit.
18. The segment thus found is to be set, on the reverse side of the rule (Fig. 2),
to either extremity of the upper line [(a) or (e)]-that is, the left 100, or the
right 100-whichever will bring the required figures within mutual compass: the
reading being that familiarised by all logarithmical slide-rules.
19. The proof-quantity is obtained by setting the strength to either 100 in like
manner, whereupon the rule indicates the required result by showing how much
is to be added to, or deducted from, the ullage, according as the spirit is over-
proof or underproof. But when both ullage and strength are very high, it is
preferable to use the enlarged division's [Fig. 2 (c) (d)], and thus get the proof-
quantities direct.
20. 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:-
A slide-rule having marked on it:-
1. A single radius of logarithmical divisions operating with a line of segments
broken into two equal parts-the said segments being either for lying casks, or
standing casks, or both :-
"
Acinals adi
FRANCIS C. FARMAR,
Applicant.