|Harold E. Gulvin. Farm Engines and Tractors. McGraw-Hill Book Co., Inc., 1953.|
The original caption reads:
"The old Model 1, completed in 1901 by Hart and Parr, weighed 20,000 lb and was rated at 22 to 45 horsepower. Today, a tractor developing about 22 drawbar horsepower weights less than 3000 lb."