174 Account of Experiments made 
Experiments made on the Bar of 4 Inches deep by 3 Inch thick, 
by giving it different Forms, the Bearings at 2 Feet 8 Inches, 
as before. 
No. Ibs. Ibs. 
153 Bar formed into a semi-ellipse, weighed 7 4000 
154 Ditto, parabolic on its lower edge an ee 3860 
Ditto, of 4 inches deep by } inch thick «e 3979 
Experiments on the transverse Strain of Bars, one End made 
fast, the Weight being suspended at the other, at 2 Feet 8 
Inches from the Bearing. 
155 An inch square bar bore as si 280 
156 A bar 2 inches deep, by 4 an inch thick we 539 
157 An inch bar, the ends made fast .. ate 1173 
The paradoxical experiment of Emerson was tried, which states 
that by cutting off a portion of an equilateral triangle (see page 
114 of Emerson’s Mechanics) the bar is stronger than before, 
that is, a part stronger than the whole. The ends were loose at 
2 feet 8 inches apart as before. The edge from which the part 
was intercepted was lowermost, the weight was applied on the 
base above, it broke with 1129 lbs., whereas in the other case 
it bore only 840 lbs. 
Remarks on the transverse Strain. 
Banks makes his bar from the cupola, when placed on bearings 
3 feet asunder, and the ends loose, tobear_ .. 864 lbs. 
Now all my bars were cast from the cupola, the difference 
was therefore Bis oe oe: ‘ee 33 Ibs, 
I adopted a space of 2 feet 8 inches asunder, as heing more 
convenient for my apparatus. The strength of the different bars, 
all cases being the same, approaches nearly to the theory, which 
makes the comparative values as the breadths multiplied into the 
squares of the depths. The halves of tke bars were tried, merely 
_to keep up the analogy. The bar of 4 inches deep, however, 
falls short of theory by 365 Ibs. It is evident we cannot extend 
the system of deepening the bar much further, nor does the 
theory exactly maintain in the case of the equilateral triangle 
by e 2 ae oe cy SOS. 
The diagonal position of the square bar, is actually worse than 
when laid on its side, contrary to many assertions *. 
* That a square bar was weakest in the direction of its diagonal, I had 
from theory determined some time ago, and the investigation is given in the 
Phil. Mag. vol. L. p. 418; and itis very satisfactory to find it confirmed 
by these experiments, and also Ly those of Mr. Barlow. 
It is not an easy task to make accurate experiments on triangular bars, 
as it is difficult to protect the angle, unless a kind of saddle be used, which 
must affect the result.—T. T. 
The 
