. 
on a New Photometer. 317 
There were produced from this mixture 102,724 cubic feet of 
gas or 4°24 cubic ft. to the pound of coal, and 40 bush. cok 
Weighing 41°5 Tbs. per bush. =1249 Ibs. from 2000 Ibs. coal. 
_ jnorder to avoid as far as practicable the errors likely to 
elevation. Observations were also made with the Carcel’s me- 
chanical lamp as a unit. The size of lamp employes was one 
our of the first 
form of lamp is regarded as furnishing the most uniform light 
‘of any artificial source for a series of Loui In the followin 
tables (see next page) the results are presented in as simple an 
conde a form as practicable. The several burners compa 
Set of burners was used in all the trials. The gas consumed was 
4 spring, (like a coach candle lamp,) was kept always at the same 
pe 
Lie 
Ose 
Span ye 
