654 



Meteorological Apparatus. 



No. 55 4.i,"> 



55 455. 1 : 5 



55 458. 1 : 7. 



55456. 1 : 18 



55 457. 1 : 6. 



55.455. Weather Telegraph after Lambrecht, Figure, with barometer, thermometer and 

 hygrometer 



The place at which the observations are to be conducted should be mentioned when ordering, 

 as also height above sea-level. 



55.456. Compression Hygrometer after Kolosy, Figure, with millimetre scale, for exact 

 measurements of the humidity-content of the atmosphere, with thermometer in 1 / 8 C., 

 for 20 to + 40 C . 



This new hygrometer is based on the measurement of the tensive force of the moisture contained 

 in the air at the time of the observation. The quantity of moisture is given in accordance With Dalton's 

 law of partial pressures, being read off direct in whole percents and ' , of a per cent. A fresh filling 

 is rc(|iiired for each measurement. Directions for use and a Table for facilitating measurements are 

 supplied with the apparatus. 



The relative humidity is determined by direct measurement, and the instrument can be used 

 for calibrating and determining the constants of other hygrometers. 



."..">. I. "i 7. Recording Hygrometer, Figure, with clockwork cylinder, making one turn every 

 week; very accurate movement 



55.458. Psychrometer after August, Figure, with two accurate thermometers in Vio 

 from --15 to + 50 C., with wood stand (M. T., p. 101) 



55.459. -- idem, with metal stand 1. 



Cl. 6558, 621i, 

 4706, 5208. 



s. (1. 



it. (i 





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