I present this Book of Practical Formulae to the various trades for whom it caters in the hope that in its pages they will find much that may be useful to them. I do not lay claim to anything original in the formulae, being well aware that many of them are old and well tried, but none the less deserving of a place in such a compilation. Every formula has been subjected to a scrutiny, and none has been inserted unless it was considered to be a practical working formula. Still a compiler can hardly be expected to have a full working knowledge of every one, so that it may be possible that one or two may not be so practical as appears on the surface. In such a case I would ask the forbearance of my readers, and it they will only bring such cases to my notice I shall be thankful to them.