442 The Smithsoniaji histitiition 



vignette already given from Lamansky's drawing will show 

 in another way the progress which has been made by 

 bolometric research. 



I have described here but one research, though that is not 

 the only one prosecuted at the observatory. Among others 

 one of more general interest is that on the "Cheapest Form 

 of Light," carried on by the joint use of the bolometer and 

 photographic processes, of which an account will be found in 

 the "American Journal of Science."^ The principal conclusion 

 of the research just named is that processes exist by which 

 light can be produced without the present waste of energy in 

 producing invisible heat along with it — a conclusion of much 

 practical importance. 



Other and subordinate researches will be described else- 

 where; of the principal one here spoken of it is proper to 

 repeat that the difficulties have been enormously increased by 

 the unsuitability of the site, and that it is to be earnestly hoped 

 that the Institution may be enabled later to provide a more 

 fitting one. 



1 Volume XL, page 97, August, 1890. 



