These ratings for Murray Radiators from American Radiators are very hard to come by. And thanks to Gerry Gill for finding and sharing the Murray patent, which you'll also find here.
This chapter on hot water heating systems and piping was prepared by Professor F.E. Giesecke (Director of Texas Engineering Experiment Station in TX) for the The American...
Here are ratings for the Erie radiator from Jarecki Mfg Co Ltd. They were based in Erie, PA and their radiators appeared in issues of Domestic Engineering in the 1890s.
Brian Roberts & Paul Yunnie compiled this document that contains beautiful vintage advertisements and illustrations of radiators from the mid to late 1800s and early 1900...