William Fletcher 
Steam Jacket [PDF ebook] 
A Treatise on the Economical Use of Steam for Engine-Builders, Engine-Drivers, Mill-Managers, and Steam-Users Genrally

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. It may be owing to this dearth of literature, in a great measure, that accounts for such widespread ignorance respecting the use of the steam-jacket prevailing among engineers. It is to many a perplex ing paradox. When engine-makers, who do not apply it, evidence some hazy notions respecting its utility, there is no occasion for surprise. But, when we find engineers at the head of one of the largest portable engine firms (who profess to have jacketed their earliest engines, and still continue the practice) saying that the cylinder is protected from cold and radia tion by’means of a jacket of steam, clearly showing that the function of the steam-jacket is not understood by the writers, it does cause some astonishment. They can, be excused on the ground above named, viz., the fragmentary nature of the information relating to this subject. One writer says Almost every engineer knows now-a — days that a cylinder should be kept as hot as possible; but very few makers of steam-engines understand the precise reasons why a cylinder should be kept hot. ‘most people imagine that the condensation takes place by conduction through the metal of the cylinder to the outside.