IMPROVED MEANS FOR FACILITATING CALCULATIONS
Year: 1862

page_text: PROVISIONAL SPECIFICATION left by Robert Dunlop at the Office of
the Commissioners of Patents, with his Petition, on the 17th January
1862.
I, ROBERT DUNLOP, of Cwm.Avon, Taibach, in the County of Glamorgan,
Accountant, do hereby declare the nature of the said Invention for "IMPROVED
MEANS FOR FACILITATING CALCULATIONS," to be as follows:-
This Invention relates to improved means for facilitating calculations,.
which means consist in a collection of leaves or strips of paper, parchment,
linen, metal sheets, or any other material or fabric, which should be made up
into a book containing a number of leaves, say, twelve leaves, as an instance,
and these leaves, each or some of them, divided into a number of sections or
smaller leaves or strips by cutting or separating them in such manner that the *
leaves may range one above the other, or, otherwise range together as may be
requisite. This book contains calculations in money, or it may be used for
calculations of other tables, such as weights and measures, or any other
calculations.
Illustrative description of the mode of operation.-Supposing the book to
be suitably arranged, and it is required to know the result of the following cal-
culation, 316 yards at 3d. per yard, the first operation is to select the
section of the book which may be devoted to calculations for quantities from
100 to 900, and this is found immediately as the section is marked
"hundreds." Having found this section, then turn over the leaves of this
section so that the place opened shews calculations for the quantity 300 ;

page_text: this is easily done, as an index to the section (similar to the indexes used in
ledgers) guides the eye to the figure required. After this is done refer to the
section marked "tens," and in like manner turn over the leaves of that
section until you have calculations for the quantity tens; and, lastly, identify
the unit section, and select the calculations for the quantity 6. Having done
this, refer to the column marked "rates" at the bottom of the book, and
select the rate you require, viz., 3d., and this will be found by addition to be
£3 19 0. In the like manner find the "rate" noted in red ink, say, the
amount will be found, viz., 16s. 5d., making a total of £4 15 5, the
result of the calculation required. Again, suppose the result of the following
calculation to be required, 54,026 divided into £2,526 10 2, in the same
manner, as for the first example, the quantity 54,026 is found' selecting
the numbers from the sections, and then first examine the amounts on the
lowest open leaf, and find the nearest amount to £2,526 10 2; this upon
reference will be found to be £2,291 13 4, above the rate 11d. Then add
up the several amounts in that column, say, those in black ink, and the result
will be found to be £2,476 3 10, deduct this from the given amount, and the
remainder will be £50 6. 4. Then again refer on the lowest leaf for the
nearest amount to the remainder, and above the rate one farthing will be
found in red ink in that column £56 5 6, consequently the result is, 11 d.
nearly. Again, addition, subtraction sums, rule of three sums may be given,
and the result ascertained by the use of the above means.
In conclusion, I would here observe that I do not confine or restrict myself
to the precise details or arrangements which I have had occasion to illustrate,
describe, or refer to,, as many variations may be made therefrom without
deviating from the characteristic nature of my said Invention, as herein-before.
described.