The experiment described on pages 8 and 9 showed that immediately the bubbles of steam reach the surface of the water and break there—that is, when simmering commences—the thermometer reaches the boiling-point, and that however violently the boiling may afterwards occur, the thermometer rises no higher. Therefore, as a medium for heating the substances to be cooked, simmering water is just as effective as ‘walloping’ water. There are exceptional operations of cookery, wherein useful mechanical work is done by violent boiling; but in all ordinary cookery simmering is just as effective. The heat that is applied to do more than the smallest degree of simmering is simply wasted in converting water into useless steam. The amount of such waste may be easily estimated. To raise a given quantity of water from the freezing to the boiling point demands an amount of heat represented by 180° in Fahrenheit’s thermometer, or 100° Centigrade. To convert this into steam, 990° Fahr. or 550° Cent. is necessary—just five-and-a-half times as much. On a properly-constructed hot-plate or sand-bath a dozen saucepans may be kept at the true cooking temperature, with an expenditure of fuel commonly employed in England to ‘boil’ one saucepan. In the great majority of so-called boiling operations, even simmering is unnecessary. Not only is a ‘boiled leg of mutton’ not itself boiled, but even the water in which it is cooked should not be kept boiling, as we shall presently see. The following, written by Count Rumford nearly 100 years ago, remains applicable at the present time, in spite of all our modern research and science teaching: ‘The process by which food is most commonly prepared for the table—BOILING—is so familiar to everyone, and its effects are so uniform and apparently so simple, that few, I believe, have taken the trouble to inquire _how_ or in _what manner_ these effects are produced; and whether any and what improvements in that branch of cookery are possible. So little has this matter been an object of inquiry that few, very few indeed I believe, among the _millions of persons_ who for so many ages have been _daily_ employed in this process, have ever given themselves the trouble to bestow one serious thought upon the subject.