214 



Intelligence and Miscellaneous Articles. 



p7 is accordingly the ratio of the weight of vapour to that of dry 



air ; it is independent of pressure and temperature, for/ and H— / 

 follow the same laws ; it expresses the hygrometric richness in 



f 

 weight, and ff j measures its volume. 



It may be remarked that the observations do not directly give 

 the ratio ordinarily used, p. In fact, the condensing hygro- 

 meter measures /, which is a function of the pressure and there- 



F'-f 

 fore of the height ; the psychrometer determines - ^x ; in order 



f 

 to pass from the measurement made to the function ^, a calcula- 

 tion is made which serves no further purpose. By introducing 

 the denominator F', we just introduce into the tables disturbances 

 arising from the temperature which mask the influence of the 

 vapour and complicate the result. It is no more difficult to 



f 

 calculate rr * and keep the result, than to calculate and retain 

 f ii ~"/ 



4; this would be replacing a complicated function, from which 



nothing can be deduced by an exact gravimetrical or volumetrical 

 measurement of the hygrometric composition of the air. 



f 

 I propose therefore to suppress the relative moisture ^ in me- 

 teorological tables, and to replace it by the hygrometric richness 



f 

 rr_, . In order to justify this substitution, I may show the 



effect by an example. I take the determinations made by 

 M. Alluard at Clermont Ferrand in 1880, and published in 

 the Annates Meteorologiques. No very appreciable differences are 

 seen in the different months ; the numbers decrease from the morn- 

 ing until 3 p.m., which shows the influence of temperature as 

 by M. Angot. Nothing in it indicates change of moisture. 



Clermont. — Relative Moisture. 



January 

 February 

 March . . . 



April 



May 



June 



July 



August . . . 

 September 

 October ... 

 November 

 December 



6. 



853 



804 

 83-9 

 81-9 

 75-6 



82-5 

 79-8 

 86-9 

 88-6 

 849 

 88-2 

 817 



9. 



89-0 

 71-6 

 59-8 

 71-6 

 58-7 

 64-4 

 60-1 

 66-2 

 67'9 

 742 

 80-8 

 772 



12. 



795 

 592 

 68-3 

 63-7 

 49-3 

 589 

 48-0 

 570 

 56-9 

 629 

 70-4 

 70-8 



3. 



795 

 547 

 390 

 61-5 

 493 

 58-1 

 41-4 

 579 

 551 

 62-2 

 730 

 797 



6. 



89-6 

 74-3 

 52-6 

 715 

 54-7 

 652 

 575 

 716 

 733 

 78-7 

 82-6 

 79-1 



9. 



90-3 



77-7 

 695 

 76-6 

 70*8 

 812 

 793 

 83-8 

 83-4 

 85-5 

 85-4 

 82-G 



