116 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



hair hygrometer, as compared with the wet and dry bulb 

 thermometers. His comparative observations extend over 

 one entire year, and he gives the following conclusions : 



1. The hair hygrometer, made by Hermann and Pfister, 

 in Berne, gives the humidity, in summer and winter, with all 

 desirable accuracy, and does not deteriorate, with careful 

 handling, in the course of years. 



2. The psychrometer, when the temperature is above freez- 

 ing, may, perhaps, be somewhat more reliable than the hair 

 hygrometer, and is certainly necessary as an occasional con- 

 trol over the latter; but in winter, with the most careful 

 manipulation, this instrument frequently gives too large a 

 value for the relative humidity, and even absurd results, 

 if constant Avatchfulness is not maintained. 



3. The differences between a number of psychrometers, ex- 

 posed in different positions, are somewhat greater in summer 

 weather than those of hair hygrometers. Schweiz, Jleteor. 



A NEW BAROMETER. 



At a recent meeting of the Association of the Lower Rhine 

 Provinces, Dr. Geissler explained a very delicate barometer 

 newly constructed by him. The details of this apparatus 

 can scarcely be properly understood without personal in- 

 spection or proper drawings. It is sufficient to say, however, 

 that it consists in inclosing a certain mass of air in such a 

 way that its volume is not influenced by changes of tem- 

 perature, but is affected directly by the changes in atmos- 

 pheric pressure. This new form of barometer is very com- 

 pact and portable ; it can be constructed of various sizes, so 

 that its sensitiveness may be made as great as desirable. 

 1(7,1873,128. 



DESCRIPTIVE METEOROLOGY. 



M. Balard, the director of the National Observatory at 

 Algiers, has presented to the French Academy of Sciences a 

 system of registering the barometer, thermometer, and other 

 meteorological elements, to which he gives the name of de- 

 scriptive meteorology. The point to Avhich he draws special 

 attention is the manner of representing in a graphic table 

 the hourly quantity of blue sky and of cloudiness. He di- 



