1920] RURAL ENGINEERING. 287 



How they test tractors at I*iirdiie I'niversity, C. H. Bkn.iamin (Ayrimotor, 

 3 {,1020), A'o. 6', pp. 19, 20, flyn. 2). — Tlie laboratory equipment for testing 

 tractors at Purdue University is briefly described and illustrated. 



The plant itself consists of (1) a treadmill or moving platform, supported 

 on driving wheels and idle rollers, and in its turn supp<trting the driving wlieels 

 or lags of the tractor; (2) a traction dynamometer to receive and measure the 

 pull of the tractor; and (3) an absorption dynamometer to control and measure 

 the energy transmitted through the treadmill and its supporting wheels. The 

 plant is capable of testing tractors weighing as liigh as 12,(XK) lbs. on the driving 

 wheels, and giving a drawbar pull of about 5,000 lbs. at a speed not to exceed 

 5 miles per hour. The tractors may be either single-wheel or double-wheel, 

 front or rear drive, or of the caterpillar type, with maximum tread for the 

 double-wheel tractor of 85 in. and a caterpillar length of 96 in., the face of the 

 drivers not being greater than 26 in. 



The Lincoln [tractor] trials, September, 1919, R. N. Twkedy {Better 

 Business, 5 {1920), A'o. 2, pp. 140-152). — The detailed data of these trials are 

 reported. 



Mechanical analysis of tractors at K. C. show, H. Farrington and F. V. 

 Hkrdman {Agrimotor, 3 {1920), No. 5, pp. 1-10, 30). — This is a mechanical an- 

 alysis of 103 tractors of 66 different makes exhibited at the National Tractor 

 Show at Kansas City, Mo., in February, 1920. 



The outstanding features were the increase in the number of unit construc- 

 tion models, the increase in the number of all-pui'pose or small general-utility 

 tractors and motor cultivators, and the arrival of the garden tractor. Prices 

 ranged from $310 to $5,750, the average price of 99 macliines being $1,899. 

 The weights ranged from 500 lbs. to 26,700 lbs., the average weight of 101 

 models being 6,326 lbs. The average (list) price per pound of all the tractors 

 at the show was almost exactly 30 cts. The highest price per pound among the 

 tractors proper was in the 2-plow class where it was 35.5 cents. The price per 

 pound in the 3-pIow and 4-plow classes was 33.2 cts. ; in the 5-plow class, 24.8 

 cts. ; in the 6-p1o\v class, 27.9 cts. ; in the 8-plow clas.s, 19.9 cts. ; and in the 

 10-plow class, 24.3 cts. 



Of the 103 tractor models at the show, 91 were machines of the wheel type 

 and 12 of the crawler or tracklaying type. Eighty models had 4-cylinder 

 engines, 16 had 2-cyIinder engines, 4 had 6-cylinder engines, and 3 had 1-cylin- 

 der engines. The vertical type of engine heavily preponderated with 83 adher- 

 ents, as against 20 of the horizontal type. 



Six reference tables covering prices and specifications are included. 



1920 tractor and implement blue book {St. Louis, Co.: Midland Pub. Co., 

 1920. pp. IflS). — This handbook contains classified data on implements and im- 

 plement manufacturers, and complete specifications for farm tractors, motor 

 cultivators, tractor plows, silo fillers, grain thrashers, buskers and shredders, 

 and tractor accessories. 



A tractor engine test, C. A. Norman and B. Stockfleth (Jour. Sac. Auto- 

 motive Engin., 6 {1920), No. 2, pp. 99-106, figs. 21). — Experiments conducted at 

 the Ohio State University on a 4-cylinder tractor engine burning both kerosene 

 and gasoline, to determine what constitutes the hest adjustment for an engine, 

 are reported. The mechanical details of the engine are describetl fully. The 

 engine was run as far as pos.sible at a series of set .speeds with the throttle 

 locked in a wide-open position. At each speed the temperature of the air to 

 the carburetor was held successively at certain fixed points, usually 70, 85, 100, 

 120, 100, 200, and 240° F. The results are graphically reported. 

 187890°— 20 7 



