NEGRETTI AND ZAMBKA, HOLBOBN VIADUCT, E.G., 



FlG. 106. 



132. Negretti and Zambra's New Pocket Boiling-Point Apparatus, 

 (fig. 106) consists of a small globular metal boiler, mounted upon a metal sup- 

 port or stand. In the base of this stand is formed a receptacle for holding and 

 burning spirits of wine, by which water in {he boiler is rapidly heated up to the 

 boiling-point. On the top of the boiler is a tube for the escape of steam during 

 the operation, and on one side is seen another tube (horizontal), into which 

 is inserted one of Negretti and Zambra's Patent Maximum Registering 

 Thermometers, very finely and carefully divided upon its stem, of sufficient 

 range for all possible elevations to be ascertained by the boiling-point of water. 



The boiler having been charged with a small quantity of water, and the 

 receptacle filled with sufficient spirit, the boiler is placed upon its support 

 above the burning alcohol, with the Thermometer bulb inserted into the side 

 tube. In a few minutes the boiling point will be attained, and the mercury in 

 the Thermometer will rise to this point, and remain in the tube until it is 

 convenient to note the temperature thus obtained. 



If, after the experiment has been made, the Thermometer be carefully 

 withdrawn from the boiler, and carried with the ~bulb-end uppermost, the record 

 of the temperature may be read off hours, or even days, afterwards. The 

 advantages of this apparatus are great simplicity, rapidity in use, and 

 portability. 



Price, in a portable case, with an extra Thermometer for Air Temperatures, 300 



133. Pocket Hypsometric Apparatus, as constructed by Negretti and 

 Zambra for Dr J. D. Hooker, of a very simple and conveniently portable form, 

 with one corrected Thermometer. Suited for rough exploring expeditions. 



2 10 



