118 REPORT—1849. 
On the Strength and Elasticity of Stone and Timber. 
By Professor E. Hopexinson, F.RS. 
This was the result of a series of carefully conducted experiments on the power of 
stone, timber and other bodies, to resist tension, compression and transverse force. 
The experiments have long been in progress, and will be very numerous and varied 
when completed ; they;will include the strength of most of the stones used in archi- 
tecture in this country, and of thirteen kinds of timber. The results of some of them 
were laid before the Association, at the Manchester Meeting in 1840; but as they are 
incomplete, the author is desirous of giving no more at present than this notice of 
them, except to state that they point to some important general conclusions. 
On a Calculating Instrument. By H. Kyicur. 
The inventor of the machines exhibited is a Mr. Slonimski of Byalystock in 
Poland. The first instrument submitted to the notice of the Section was one for 
performing the arithmetical processes of addition and of subtraction. It consists of 
a thin box of wood or metal, covered by a plate of metal, in which are perforated a 
convenient number of circular apertures and openings, around which are engraved 
or marked the several figures or digits 0 to 9, and behind which are indented plates 
or wheels, having in each a suitable number of teeth, some of which are shaded, or 
black, the others being left clear, or white. A small pointer, or style, is furnished 
with the instrument, for the purpose of turning round the indented plates or wheels, 
by inserting the instrument between two contiguous teeth, and moving it in the rem 
quired direction. The style is required to be inserted between those two teeth which 
appear under the particular figure engraved on the plate, which corresponds with 
the number required to be added or subtracted; one general rule being to be 
attended to, viz. that if the style be placed between two clear or white teeth, it must 
be turned to the extreme right-hand of the circular opening; but if between two 
dark teeth, it must be turned to the extreme left-hand thereof. The upper part of 
the instrument is to be used for addition, and the lower part for subtraction, as en- 
graved thereon. The multiplication instrument consists of a rectangular box, about 
15 in. square and 3 in. deep. It contains cylinders having printed tables of figures 
on the circumference of each, which cylinders revolve separately, by means of the 
knobs at the bottom of the box ; and by other knobs, the upper part of each cylinder 
is moveable in a vertical direction also, the rotative and the vertical motions being 
regulated by figures termed indices, that appear through small holes over the axes 
of the cylinders. In addition to the index holes, there are nine other rows of holes, 
on the surface-plate of the instrument, the lower row of holes being for the mul- 
tiplicand, and the corresponding rows of holes above it to exhibit the products of — 
that multiplicand by each of the nine digits; and these products are produced 
almost immediately, and without requiring any mental effort. The horizontal 
number of holes in this instrument is eight ; and it is therefore calculated to give — 
the product of any number having seven places of figures, or to millions, what- 
ever may be the order of those figures. This instrument is the result of a new 
theorem of figures discovered by M. Slonimski. 
On a New Rotary Engine. By the Rev. J. W. M‘Gautry, Professor of 
Natural Philosophy to the Board of National Education, Ireland, Se. 
The following are the facts, &c.-deduced from a series of experiments, made by 
myself and the Messrs. Allingham of Dablin, conjointly. The species of engine to 
which they have reference is exemplified by the model, now working before the 
Section. 
No one knew better than Watt the excellence of the ordinary engine, and yet he 
was extremely anxious to construct a rotary engine: indeed he, with this object, 

