366 
MESSRS. W. B. WILSON AND P. L. GRAY 
The dimensions of the strip were :— 
Length.102 millims. 
Breadth (including ledge) .... 12 ,, 
Thickness. 0-01 millim. 
Fig. 2 shows the final form of the instrument with the water-jacket removed. 
It was made by Messrs. Yeates and Sons, Dublin. 
Fig. 2. 
A 
S is a block of slate, 17^ X 9 X 3 cent!ms., rigidly fastened to a cylinder of brass, 
B.C., which can be worked up and down a square brass pillar, _B.P., by means of the 
pinion P. 
The pillar is screwed firmly to a heavy slate base-plate, on which the radio¬ 
micrometer also stands. The platinum strip, Pt., is held between two forceps, of 
which one, F, is fixed, and the other, F, is free to rotate on an axle which is sup¬ 
ported between A and B. In this way the jaws of the forceps, F, which hold the 
strip between them, can move, when the strip expands, in a small circular arc, which 
