118 Scientific Proceedings, Royal Dublin Society, 
And, finally, at a subsequent meeting of the Society, Mr. Peter 
Spence brought forward a series of tension experiments showing 
an increase of 3°5 per cent. in the strength of iron co-incident with 
a reduction in temperature from 60° to zero, Fah. 
A few days before the late Arctic Expedition sailed from Eng- 
land Mr. Draper drew my attention to abstracts of the two last 
sets of experiments published in the Chemical News. The cold of 
a polar winter would afford decided facilities for such experiments, 
and, moreover, they demanded no special skill on the part of the 
experimenter. There was, however, very little time to make pre- 
parations, but on mentioning the subject to Sir Leopold M‘Clin- 
tock, Admiral-Superintendent of Portsmouth Dockyard, I at once 
obtained every facility, and before the ships sailed a small num- 
ber of cast iron bars were prepared for me, together with a suitable 
weight to test them with, and a little guillotine to drop it from. 
The bars were of first-class mixed metal, cast from the same 
ladle. They were cut to as nearly as possible the same size, 
namely, ‘95 centimetre square, and 15:2 centimetres long. There 
were eighteen of them. They averaged 1046 oms., the extremes 
being 103°5 and 1050. They were packed away in my cabin 
in a temperature never below 40°, and in “winter quarters,” 
when the cold became intense, experiments were begun. 
In testing each bar it was supported on two knife-edges at the 
base of the guillotine 12°7 centimetres apart, and subjected to a 
blow from a falling weight of 1082'14 gms., so arranged as to strike 
with an edge of 100° evenly across the centre of the bar. The 
weight fell altogether free, and the height of the drop was regu- 
lated by means of a centimetre scale. 
It was first necessary to ascertain the strength of the bars at 
ordinary temperatures. Bars were therefore tested in and at tem- 
peratures of 65° and 40°, with the following results :— 
Temperature 55° (Fah.) No. : bore ap broke with 30°5 centimetres fall. 
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