RUKAL ENGINEERING. 485 



How horsepower is to be computed (Farm Machinery, 1912, No. 1011, pp. 

 15, 17). — A general discussion of the methods of computing the power and 

 efficiency of machinery with special reference to agricultural tractors, explain- 

 ing the actual difference between indicated and brake horsepower, and stating 

 as the factors to be considered in a comparison of the tractive horsepower of 

 engines, the mean effective pressure, piston ai'ea and speed, dead weight of 

 engine, and ground surface. 



What electricity will do for the farmer (Conn. Farmer, 42 (1912), No. 21, 

 p. 9). — Results of tests made on farms by a corps of engineers from an elec- 

 trical appliance company are given, showing the different amounts of work 

 done in a given time by different farm machines driven by electricity and the 

 cost of the operation in each case. 



An experience with electric motors, D. R. Palmqitist (Country Gent., 77 

 ( 1912 ) , No. 23, p. 5, figs. 2 ) . — Some actual cost figures for the work done by a 

 15-horsepower portable motor on an average farm are given and compared with 

 the costs of doing the work by other methods. The motor cost $260 and the 

 power was supplied at 3 cts. per kilowatt hour. Some of the comparisons are 

 as follows : 1,700 bu. of grain were threshed for $6.60, the cost of doing this by 

 steam or gas tractor being $9 ; 4,000 bu. of corn were ground for $160, the cost 

 at the nearest mill being $308 ; and fodder shredding cost $2.74 per ton, a 

 neighborhood custom machine charging $3 per ton. 



Electric farm lighting' plant installation, G. D. Habris (Gas Engine, H 

 (1912), No. 6, pp. 332-335, figs. 2).— A brief discussion of the practicability of 

 small lighting plants, their successful operation, and the size, equipment, and 

 cost of a plant most applicable to the average farm. 



[Tests of implements], G. Fischer et al. (Arh. Deut. Landw. Gesell., 1911. 

 No. 199, pp. 80, figs. 63). — Descriptions and the methods and results of com- 

 petitive tests are given of subsoil plows and pond-weeding machinery, with the 

 results of preliminary examinations of several improved agricultural imple- 

 ments, among which are improved manure spreaders, rollers, straw presses, 

 potato diggers, turnip headers, cultivators, mowers, and stump pullers, and the 

 results of individual tests of subsoil packers, motor threshers, manure spreaders, 

 and road tractors. 



A new driving wheel for power plowing outfits, A. M. Leoni (Gas Engine, 

 U (1912), No. 6, pp. 316-318, figs. 3).— A driving wheel is described which is 

 equipped with a number of spades, and operated by an eccentric in such a way 

 that with the rotation of the wheel they ai'e pushed into the soil vertically, 

 one after another, providing fixed points of power application for the forward 

 movement of the vehicle and causing a minimum loss of energy. 



Automobile mowing machines and motor-driven mowers, M. Ringexmann 

 (Jour. Agr. Prat., n. ser., 28 (1912). No. 19, pp. 592-594) .—These 2 types of 

 machine and their operation are described. It is claimed that with the auto- 

 mobile mower about 4,000 square meters (about 1 acre) of hay or other forage 

 can be mowed in an hour. The motor-driven mowing machine requires 1 man 

 and only 1 horse to do the work of an ordinary 2-horse machine. 



Trials with small self-cleaning threshing machines, 1911, C. V. Birk and 

 C. L. Feilbeeg (Tidsskr. Landdkonomi, 1912, No. 3, pp. 161-224, figs. 11).— 

 Eighteen different machines were examined and tested by the committee on 

 machinery trials of the Royal Danish Agricultural Society. The report gives 

 the results of the trials and the judgment of the committee as to the strong 

 and weak points of the different machines. 



Spraying apparatus, H. A. Surface (Bi-Mo. Zool. Bui. Pemt. Dept. Agr., 2 

 (1912), No. 2, pp. 68-77, pis. 5). — A general discussion is given of apparatus 

 for spraying orchards and field crops, including descriptions of various types 



