boiler; this is almost as true as to mental as it is to physical power.
There are innumerable treatises upon the feeding of animals; upon the generation of steam; upon the construction and ventilation of buildings; upon the arts which relate to clothing the human body, and upon keeping the dwelling and workshop warm; and, lastly, yet more numerous treatises or cookery-books upon the art of mixing and preparing the food which is to be cooked; there are also many treatises, chemical and physiological, upon the subject of nutrition, and there are one or two treatises on the science of cooking, notably Dr. Mattieu Williams's "Chemistry of Cookery"; yet, so far as the writer has been able to ascertain the facts, there is no receipt-book or cookery-book in common use which deals with the actual art of cooking by directing the right application of heat for a suitable time and at a suitable degree, to the specific food which is to be converted into a nutritious form by the conversion of its elements into new forms or conditions by the action of heat upon it.
It is possible that greater attention has been given to this matter in England than in this country. After trying in vain to find an oven thermometer in the United States, I lately imported one from England, made by Joseph Davis & Co., Fitzroy Works, London, S. E., and purchased at an agricultural show at retail for seven shillings sixpence, gauged at 200° to 600° Fahrenheit. On this thermometer are marked the respective degrees to which various kinds of food should be subjected, as follows:
These figures agree substantially with my own experiments as to the maximum of heat, but I do not concur with the inference that less than 200 Fahr. may not be permitted, if time be given for the lower degree of heat to do its work. On the contrary, any kinds of very tough meat may be reduced to a very tender condition by the long application of heat at 180 to 200, without loss of flavor or nutritious property, provided the food be put into substantially air-tight vessels. The testimony of Dr. Mattieu Williams is conclusive on this point, as well as the special knowledge of the few good cooks of the method of simmering as distinguished from boiling. Meats and grains may be most nutritiously cooked at less than a boiling heat, and eggs should always be; while most kinds of roots, tubers, and vegetables require a higher degree.
I venture now to give some of the general conclusions which I have reached by the application of somewhat crude methods and