150 BULLETIN 1059, IT. S. DEPARTMENT OF AGRICULTURE. 



For all stations the dial reading should be recorded in the field at 

 each observation, and the dial readings and total movements should 

 be tabulated in adjacent columns of the "Humidity, Wind, and 

 Evaporation" form. The decade means or sums and the monthly 

 sums and means should be computed and entered. For most uses 

 the decade sums will be preferable to means. The record of day and 

 night movements may be obtained either from two dial readings 

 per day, or from hourly automatic records. 



Where hourly records are available, the greatest wind movement 

 for any single hour of each day should be entered, and also the total 

 wind movement by day and by night; that is, from 6 a. m. to 6 p. m., 

 and from 6 p. m. to 6 a. m. This division of the daily movement is 

 of interest in the general study of the climate, and may assist, for 

 example, in determining relative amounts of evaporation during the 

 day and night, when this is not readily determined directly. 



The monthly, annual, and growing season means of the movements 

 obtained from dial readings, and of maximum hourly velocities, and 

 the sums of day and night movements obtained from automatic 

 records, with the mean hourly movements computed therefrom, may 

 be tabulated on the " Summary " form. 



Instruments. 



Self-registering Instruments : 



Single register complete (for wind velocity), with a year's supply 

 blank Forms 1015, pen and ink (by special arrangement a reg- 

 ister to carry wind record for one week may be obtained) $95.00 



Two magnet registers — 



No. 2, for wind velocity and sunshine (using Form No. 



1015-C) 125.00 



No. 3, for wind velocity and rainfall (using Form No. 



1015-D) 130. 00 



No. 4, for wind velocity, rainfall, and sunshine (using Form 



No. 1015-E) i 140. 00 



Quadruple register complete (for wind direction, wind velocity, 

 rainfall, and sunshine), with a year's supply of blank Forms 



1017, pens and ink 275. 00 



In all of the above, cable and battery for electrical installation 

 are extra. 

 Anemometers, wind vanes, and supports : 



Anemometer, Robinson's ; of the standard pattern, complete with 

 aluminum cups and wrench ; all dimensions and construction to 

 be identical and small parts interchangeable with corresponding 



parts of the anemometer of the Weather Bureau 52. 00 



Anemometer cups, aluminum, with arms, G. S. S. No. 12200; per 



set 8.00 



Anemometer cups, copper, reinforced, .013 inch thick, hemmed at 



edges and arms reinforced, G. S. S. No. 12201 ; per set 9. 50 



Wind vane; small, for towers, with mounting, complete, G. S. S. 



No. 12274 13. 50 



