WEATHER BUREAU. 67 



SPECIAL SERVICES. 



Few clianges Avere made cliiriiio- the year in the special crop services 

 maintained by the Bureau and described sufficient!}' in the last annual 

 report. The cotton, corn, and wheat services "were improved during 

 the year by the inauguration of a new system of making observations 

 Avhereby the minimum temperatures experienced during the preced- 

 ing nigiit were reported instead of the 24-hour minimum. 



A new method of issuing reports Aveekly, instead of daily, in the 

 cattle region service, has proved very satisfactory, and resulted in a 

 material reduction of expense. There is an insistent public demand 

 for the extension of this service over some important grazing dis- 

 tricts not yet covered, which it is hoped to meet in the near future. 



Special studies were made during the year in the development of a 

 mathematical hygrometric formula to aid in making more accurate 

 minimum temperature forecasts. 



The, special forecast and loarmng service was extended, with good 

 results, in connection with spraying operations in some important 

 fruit growing districts. So far as the depleted personnel of the 

 Inireau would permit, trained officials of the "Weather Bureau were 

 detailed to special field duty in fruit districts during critical periods 

 for the purpose of giving advice as to the best time to conduct spray- 

 ing operations. It is hoped that, when more normal conditions pre- 

 A'ail, the Bureau may be in position to enlarge and improve this 

 branch of its activity. 



Cooperation. — By request of other departments of the Government, 

 and for the use of the recent Peace Conference at Paris, the Weather 

 Bureau prepared, during the fall and early Avinter, a general sum- 

 mary of the climate of Africa, with special attention to that of the 

 former German colonies. A vast amount of climatic data was com- 

 piled, and a number of charts were prepared shoAving graphically the 

 annual and monthly distribution of precipitation and temperature 

 OA'er the continent, together with a discussion of its climatic char- 

 acteristics. 



The Weather Bureau continued its cooperation Avith other bureaus 

 of the department in maintaining special meteorological stations at 

 A'arious points in different sections of the country as an aid to research 

 and inA'estigation of the many agricultural problems in which Aveather 

 is an important factor. 



INSTRUMENTATION. 



The instrumental equipment of the A\arious stations of the Bureau 

 has been maintained at the high standard of former years. The prac- 

 tical cessation of European supply and the difficulties attending 

 American manufacture of instruments have made it less simple than 

 heretofore to obtain suitable supplies, particularly Avhen such sup- 

 plies iuA^olved the labor of highly skilled artisans. Prices of instru- 

 ments and of parts have increased greatly, and Ave have been able to 

 maintain the equipment of the Bureau with the appropriation avail- 

 able only by Avorking oA^er a considerable stock of apparatus aA'ail- 

 able. The instrument shop of the Bureau has been availed of to sal- 

 vage instruments that under ordinary conditions would hardly be 

 worth repair. Naturally a time Avill soon come when further opera- 



