All bolts and
studs 3/4 in. diameter and above, screwed into boilers, have 12
threads per inch, sharp thread, a taper of 1/16 in. per 1 inch; tap
drill should be 9/64 in. less than normal diameter of bolts.
The table is based upon the following general formulae for certain
dimensions:
Short diam. rough nut or head = 11/2 diam. of bolt + 1/8.
" finished nut or head = 11/2 diam. of bolt + 1/16.
Thickness rough nut = diameter of bolt.
Thickness finished nut = diameter of bolt - 1/16.
Thickness rough head = 1/2 short diameter.
Thickness finished head = diameter of bolt - 1/16.
* * * * *
AN ENGLISH RAILWAY FERRY BOAT.
[Illustration: AN ENGLISH RAILWAY FERRY BOAT.]
The illustrations above represent a double screw steam ferry boat for
transporting railway carriages, vehicles, and passengers, etc.,
designed and constructed by Messrs. Edwards and Symes, of Cubitt Town,
London. The hull is constructed of iron, and is of the following
dimensions: Length 60 ft.
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