Immediately after tile a(0om'nment of' the February meeting of' this INSTITUTE~ the drum having fiat east iron he'tds, w'ls tested by hydrostatic pressure, for the purl)ose of" ascertaining the strength of such heads.
The dimensions of the drum were four thet in length bv ihlrty-six inehes in diameter, the heads were of cast iron, of 18,000 lbs. tensile strength per square in(-h of (:ross section an(1 one and fifteen sixteenths inches (1}~-) thick; in one head was a man-hole opening of about 10 x 14 inches, 1)elow it a fi~ed inlet of two inches diameter and having a flange ihstened thereon i)y fbur ~ stud bolts and nuts; there were three openings fbr guage cocks and two for "t glass water guage eonnecthm, such as is usual in cylinder boilers having this ti)rm of head. These openings were closed with serew plugs, the man-hole opening by a plate not. planed, but simply east with a flat bearing surhee, and a g~ket of vulcanized India rubber, interposed between it and the slightly raised bearing on the inner surfhee of the tread which had been planed flat.
The other head was simply a casting without any 1)erforations therein excepting of course the rivet holes in the flange.
This dr~ml or cylinder was made by the same parties, Messrs. Sidebotham & Powell, of Franktbrd, who made the boiler which exploded in Gafney & Nolen's dye works, on Martha Street above Huntingdon Street, Philadelphia, on May 25, 1881, and the heads were east from the same pattern, and fitted as nearly as they could be in the same way as the burst boiler head, the remaining parts of which were produced at the February meeting.
The tests was made wifll a force-pump, having a ~-in. diameter ram and two pressure guages, each provided with a maximum registering hand, and graduated in 25 lbs. divisions.
The following results were shown: at 425 lbs. to the sq. in. the longitudinal seam leaked just enough to show a wet line, ~ did also a snmll part of the seam betwe, en the cast iron head containing the manhole; at 550 lbs. the head cracked so as to make a noise, but showed very little leakage, the cracks being two radial ones tยฅom the man-hole opening~ and one some 10 inches around the riin or flange, where it