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PROFESSOR OSBORNE REYNOLDS AND MR. J. H. SMITH ON A 
chaser to a Whitworth Standard f-inch thread. The pieces were marked off to a 
standard length and the ends cut down well below the thread. The central part 
was roughed out and turned carefully as the size required was approached, a template 
being used for the curved ends, which were cut to an arc of a circle f inch diameter. 
The specimens were next rotated between centres and ground to size by means of 
a small emery wheel which rotated rapidly in the opposite direction to the specimen, 
and which was moved backwards and forwards parallel to the axis of the specimen. 
The amount taken off during the grinding process was usually about one-thousandth 
part of an inch all over the central parallel part. 
In the early part of the work the specimens were turned, ground, and finished in 
the College Laboratory, but during the latter part they were prepared by Messrs. 
Carters and Co., Engineers, Salford. 
A number of specimens were turned and ground very roughly in order to see the 
effect of any bad workmanship, but the results were found to agree almost as well as 
if the specimens had been turned and ground in the careful manner above described. 
In the case of the cast-steel specimens the bars were sawn up and the short 
pieces were then annealed in a gas furnace before commencing the turning process. 
The Annealing of the Specimens. 
The finished specimens which were to be annealed were placed inside a piece of 
wrought-iron piping, 6 inches diameter, and the pipe was closed at both ends by 
means of two cast-iron covers. The case so formed containing the specimens was 
placed so as to stand with the specimens vertical, inside a gas furnace, and heated. 
The jet of hot gases was prevented from playing directly on the case by using a 
cast-iron plate which was placed opposite to the jet, and the case was rotated 
frequently to ensure uniform heating. The supply of gas and air to the burner 
could be adjusted as required. The process of heating up to a red-heat usually took 
about half an hour, during which time the specimens were occasionally examined by 
moving the upper cast-iron cover; the gas supply was then diminished so as to keep 
the furnace at a constant temperature for another half-hour, after which the burner 
was taken away, the passages for outlet and inlet of hot gases plugged up by pieces 
of cast-iron, and the whole allowed to cool, the cooling process usually taking from 
10 to 12 hours. 
On taking the specimens from the annealing furnace the thin coat of oxide was 
removed from the central parallel part by rubbing it with the finest emery cloth. 
This coat was, as a rule, easily removed, but in a few cases the specimens were 
polished in a lathe, as the skin was found to be very hard. 
The diameter of the central part was next measured by means of an ordinary 
micrometer gauge, and if this part was found to be slightly tapered, the diameters at 
the centre and each end were measured. 
