Now all of this is nice for you to know, and it may start you on a higher course, it will not make you handle your engine any better, but it may convince you that there is something to learn.

Suppose we give you a little touch of rules, and formula in boiler making.

For instance you want to know the percent of strength of single riveted and double riveted as compared to solid iron. Some very simple rules, or formula, are applicable.

Find the percent of strength to the solid iron in a single-riveted seam, 1/4 inch plate, 5/8 inch rivet, pitched or s.p.a.ced 2 inch centers. First reduce all to decimal form, as it simplifies the calculation; 1/4=.25 and 5/8 inch rivets will require 11/16 inch hole, this hole is supposed to be filled by the rivet, after driving, consequently this diameter is used in the calculation, 11/16 inches=.6875.

First find the percent of strength of the sheet.

P-D ----- The formula is P = percent.

P = the pitch, D = the diameter of the rivet hole, percent = percent of strength of the solid iron.

2 -.6875 -------- Subst.i.tuting values, 2 = .66.

Now of course you understand all about that, but it is Greek to some people.

So you see I have no apologies to make for following out my plain comprehensive talk, have not confused you, or lead you to believe that it requires a great amount of study to become an engineer. I mean a practical engineer, not a mechanical engineer. I just touch mechanical engineering to show you that that is something else. If you are made of the proper stuff you can get enough out of this little book to make you as good an engineer as ever pulled a throttle on a traction engine. But this is no novel. Go back and read it again, and ever time you read it you will find something you had not noticed before.