An essay on the boilers of steam engines Author:Robert Armstrong Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: power; this latter question we propose to consider principally in the first three chapters of this essay. 2. The only rule for adjusting the dimensions of boi... more »lers, if rule it be, that is generally agreed on amongst engine and boiler makers, is to endeavour to have them larger than necessary — hence it has become a common observation, that a ten horse engine ought to have a twelve or fifteen horse boiler, or a twenty horse engine ought to have a thirty horse boiler, and so on. It is true that some vague notions have long existed amongst working engineers, as well as with some writers on the subject, that there ought to be about five square feet of surface of water, or of the largest horizontal section of the boiler, for each horse power, and about twenty-five cubic feet of space for the same. The first of these data has become common amongst enginemen as their only acknowledged rule for roughly estimating the power of a boiler, although both it, and the mode of estimating by the cubic capacity, have generally been scouted by scientific engineers, but with how little reason, while the latter could not furnish us with better methods, we shall see in the sequel. After consulting the works of Farey, Tredgoldf, and others who have treated on this subject, besides discussing the matter with various eminent scientific persons, as wellas experienced manufacturers, we were fully convinced of the necessity of obtaining and comparing a great number of experiments on a large scale and under a variety of circumstances, in order, if possible, to deduce rules that might at least be applicable to those forms of boilers in general use. A Treatise on the Steam Engine, Historical, Practical, and Descriptive. By John Farey. London, 1827. Vol. I., quarto. f The Steam Engine, comprising an ...« less