AGRICULTURAL ENGINEERING. 797 



on a mill as the -wind velocity increases. When the velocity is low — say 6 miles per 

 hour — the load should he small enough to enable the wind wheel to run at a rapid 

 r; ,te — the rate for maximum power — and then as the wind A-elocity increases the load 

 should he increased so as not to allow the wheel to run at a higher speed. This is a 

 very promising field for the inventor. 



"If the load can not be automatically increased as the wind velocity increases, 

 then the question arises, What is the proper or most economical load ? This depends 

 on the velocity of the wind each month at the given place. During the months of 

 July and August there are a greater number of hours of low wind velocity than dur- 

 ing any other 2 months of the year. The load should be light during these months 

 for the greatest power. . . . 



"The useful work that a windmill will do when working under a constant load at 

 all velocities is small, the horsepower varying as the first power of the velocity. By 

 some device for automatically increasing the load as the wind velocity increases, the 

 power may be much increased at high velocities, and will then vary as the second 

 power of the velocity. Even with this device for increasing power there is still a 

 great difference between the power possessed by the wind and the power developed 

 by the mill, and this difference increases as the velocity increases." 



An experiment with a steam drill, C. H. Pettee {New Hampshire 

 Sta. Bui. 46, pp. 59-76, pis. 7). — An account is given of the improve- 

 ment of a street in the town of Durham commanding the approaches 

 to the college. In carrying out this work it was necessarj to reduce a 

 hill 510 ft. in length to a uniform grade (1 in 20 and 1 in 22), to make 

 several fills, and to remove the masses of rock which encroached upon 

 the roadway and forced it to one side. For the latter purpose a portable 

 steam drill capable of drilling 4 to 5 ft. per hour was used. 



Tables give the cost of equipment, blasting rock, and handling mate- 

 rial, from which it appears the cost of handling rock, including the work 

 with the drill, was $1.11 per cubic yard and was greater than that of 

 the earth fill. 



"There is need, however, of a large amount of rock work upon the 

 average country road. The steam drill is absolutely essential for the 

 economical handling of considerable rock masses, and is capable of 

 doing exceedingly economical work, in portable form, for small amounts 

 of work in a place." 



The comparative cost of moving different road materials and the 

 question of a standard grade are briefly discussed. 



A practical study of road maintenance, C. H. Pettee {New 

 Hampshire Sta. Bui. 46, pp. 77-88). — This is a report of a critical study 

 of the work of the highway agents of the town of Durham during the 

 year ending in March, 1897, and includes comments on the keeping of 

 accounts and general management, road surfacing, road machines, 

 highway laws, and public opinion on highway maintenance. 



Irrigation practice on the Great Plains, E. B. Cowgill ( Water Supply and Irrig. 

 Papers, U. S. Geol. Survey, Xo. 5, pp. 39, pis. 12, Jigs. 8).— This paper gives the expe- 

 rience of a practical farmer and irrigator with methods of utilizing the water 

 resources of semi-arid areas, and is devoted to the following topics: Eeservoirs for 

 storm waters, reservoirs for pumped water, ditches, distributing water, methods of 

 watering, cultivation, subirrigation, amount of water required, and winter irrigation. 



