ON GASEOUS EXPLOSIONS. 181 
suction temperature to be made while the engine was working not 
only under normal conditions but under special conditions, during 
which the richest possible mixture was used and the temperature 
reached at explosion was considerably higher than that occurring in 
practice. The thermometer itself consisted of a piece of platinum 
wire about 0°7 inch long and ,1,, of an inch in diameter, arranged 
with compensating leads. It is placed in a thermometer-valve, which 
is inserted through the spindle of the admission-valve in the manner 
shown in fig. 1, in which P is the platinum thermometer, and T is 
the head of the thermometer-valve, which is inserted centrally in the 
A G 
\ 
B N 
Lae | Sos 
(ft ¢ 
\ E 
Tp LAY SHAFT OF 
GAS ENGINE. 
Fic. 2. 
admission-valve A. The spring S serves to close the admission- 
valve, and the spring U serves to close the thermometer-valve. The 
main casting, C, carrying these valves is bolted to the engine in the 
ordinary way. A separate cam is mounted on the half-time shaft to 
operate the central thermometer-valve, and the complete arrangement 
is shown in fig. 2, where E is the cam; / and L are levers keyed to the 
supplementary shaft Q, which is carried on the casting F'; the spring 
S maintains contact between the end of the lever / and the cam. The 
end of the thermometer with the leads projecting is shown at B. 
The lever L is in contact with the nut N on the thermometer-valve. 
The cam is so designed that during the explosion period the valve 
