10 



L. CASELLA'S CATALOGUE 



FIG. 28. 



FIG. 39. 



25. Standard Thermometer^ Comparative, as No. 24, with porcelain scale en 



mahogany, for out-door use, range about to 130, as made by L. C. for 

 various departments of the Government (fig. 25, p. 9) 25 



26. Kew Observatory Thermometer (Meteorological Office and Admiralty pattern], 



12 inches long, with divisions etched on the stem, and the figures indelibly 

 burned on the porcelain scale, range about to 120 ; with verification from 

 the Kew Observatory, as arranged at the Brussels Conference, for taking- 

 reliable observations at sea. This is an excellent instrument, by which 

 others may at any time be compared, within the range stated, and is, 

 moreover, the only kind of thermometer which can be used at sea without 

 deteriorating from the corrosive action of salt-water and damp, in copper 

 case (fig. 26, p. 9) . . . , . 015 G 



N.B. A set of six thermometers as No. 26, with two copper cases, in a neat box, as supplied 

 by L. CASELLA to the Board of Trade and Admiralty . . 3 3 



27. Kew Observatory Thermometers, a set of six, as above, with 1 each maximum 



and minimum thermometers, for use on board of ship 4 10 



CASELLA'S STANDARD MAXIMUM THERMOMETERS. 



These registering instruments are made on the principle designed by Professor 

 Phillips, F.R.S., of Oxford, and were first employed for meteorological purposes at 

 the Eoyal Kew Observatory in 1851, by John Welsh, F.K.S., director of that establish- 

 ment. Next to its ingenious inventor, L. CASELLA claims the exclusive merit of the 

 introduction and arrangement of these most perfect maximum thermometers. In 

 the report of the Kew Committee of the British Association for the Advancement of 

 Science in 1856, they are described as " valuable for their extreme simplicity," " capable 

 of greater accuracy than any others," "the most convenient form of all maximum 

 thermometers." In 1862 they were amongst the chief causes of the decision of the 



