9(3 General A. W. Greehj — Geof/rapJiy of tlie Air. 



scattered over the world relative to, and in the interest of, the 

 United States. 



The great value set on this publication l^oth b}^ skilled meteor- 

 ologists and by the reading public of this and other countries 

 has Ijeen a source of astonishment and gratification to other 

 chiefs and to myself. 



As to the opinion of the distinguished meteorologists abroad, 

 recalling the saying that imitation is the sincerest form of flat- 

 tery, it is to be remarked that monthly pu1)lications similar in 

 literary form and substance have l^een instituted in Canada, 

 Germany, Great Britain, India, Jamaica, Mexico and Victoria. 



Among other valuable compilations and graphic representa- 

 tions of climatic data for the United States in general published 

 by the Signal service may be mentioned : 



1. Isothermal charts for each month of the j^ear, based («) 

 on observations of ten years, and also (/>) on observations of 

 eighteen years. 



2. Charts of normal temperature at 8 a. m. and 8 jj. m. for 

 each decade in the year. 



3. Charts of absolute maxima and minima in each decade and 

 also for each year at all Signal service stations (awaiting press). 



4. Charts of isotherms and isobars and prevailing winds for 

 each month from January, 1871, to 1873. inclusive. 



5. Tables indicating diurnal fluctuations of temperature for 

 each hour and month at 47 typical and representative stations. 



6. Charts and tables of average dates of first kilHng frosts of 

 autumn and last killing frosts of spring. 



7. Charts and tables showing the normal rainfall for each 

 month based on record (a) of 10 years ; (h) of 18 years ; (c) of 

 20 years (May and June; rest awaiting publication). 



8. Charts and tables showing the rainfall for each month from 

 January, 1870, to December, 1873. 



9. Excessive precipitation for month, day and hour at all 

 available stations from establishment to 1890. 



10. Charts for each month, showing the probability of rain at 

 all Signal service stations as deduced from 18 years' observations. 



11. Charts and tables of possible annual evaporation. 



12. Charts of average cloudiness for each month of the year. 



13. Charts of most frequent wind-direction and average hourly 

 ■velocities at 65 typical and representative stations at 8 a. m. and 

 8 p. m. 



