w of the
tremendous outlay for damages. This goes to show that money has not
been spared to obtain rapid transit.

After all, the means to be depended upon when one desires to make a
rapid trip from one part of the city to another is the really
admirable, cheap, always ready, convenient and comfortable London
hansom; while the way to see London is from the top of an omnibus, the
most enjoyable, if not the most expeditious, means of conveyance.

* * * * *

[Continued from SUPPLEMENT, NO. 809, page 12930.]

RIVETED JOINTS IN BOILER SHELLS.[1]

[Footnote 1: A paper read at a meeting of the Franklin Institute.
From the journal of the Institute.]

By WILLIAM BARNET LE VAN.

[Illustration: FIG. 11.]

Fig. 11 represents the spacing of rivets composed of steel plates
three-eighths inch thick, averaging 58,000 pounds tensile strength on
boiler fifty-four inches diameter, secured by iron rivets
seven-eighths inch diameter. Joints of these dimensions have been in
constant use for the last fourteen years, carrying 100 pounds per
square inch.

_Punching Rivet Holes._--Of all tools that take part in the
construction of boilers none are more important, or have more to do,
than the machine for punching rivet holes.

That punching, or the forcible detrusion of a circular piece of metal
to form a rivet hole, has a more or less injurious effect upon the
metal plates surrounding the hole, is a fact well known and admitted
by every engineer, and it has often been said that the rivet holes
ought all to be drilled. But, unfortunately, at present writing, no
drilling appliances have yet been placed on the market that can at all
compare with punching apparatus in rapidity and cheapness of working.
A first-class punching machine will make from forty to fifty holes per
minute in a thick steel plate. Where is the drilling machine that will
approach that with a single drill?

The most important matter in punching plates is the diameter of the
opening in the bolster or die relatively to that of the punch. This
difference exercises an important influence in respect not only of
easy punching but also in its effect upon the plate punched. If we
attempt to punch a perfectly cylindrical hole, the opening in the die
block must be of the same diameter as the point of the punch, or, at
least, a very close fit. The point of the punch ought to be slightly
larger in diameter than the neck, or upper part