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400
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state the dimensions. All the bars were cast 15 inches long and in breaking them for transverse strength they rested on pointed supports, 12 inches centers. The last two columns in the Tables give the computed relative strength. The outside column is used only for the half-inch square bars, so as to illustrate two methods of figuring, and is obtained by multiplying the breaking load by eight, a method advanced by some, for one-half-inch bars.* The inner is obtained by the rules shown in Chapter LXL, page 476. The area of a bar 1.1284 inch in diameter is equal to the area of one inch square; by keeping this in mind the figures in the micrometer columns can have their relation to a square inch readily denned.
TABLE 89. —TRANSVERSE TESTS OF GUN METAL.
in <u JH 6 fc	Common rule measurement.	Microm't'r measurement.	Deflection.	Broke at in pounds.	Strength per square i n ch in pounds.
i 2	Rough bars. % in   square .....	.491 in. .501   "	.120 in. .115 "	3/6 420	1,560   3,008 Ji673   3,36o
3 4 5	Planed bars. yz in. square .....	.491 in. •495  " .494  "	.250 in. .270 " .200 "	384 360   . 316	i,593   3»072 1,469    2,b8o I»295   2,582
6 I	Rough bars. i in. square ...........	1.002 in. 996 " i 044 "	.090 in. ,085 " •OQ5  "	3»5°° 3,3*) 3,428	3,486   ... 3,400   ... 3.H5    ...
9 10 ii	Planed bars, i in. square ...........	1.007 in. 1.005 " 1.005 "	.130 in. .120  " .110  "	3,140 3,095 3,072	3,096    ... 3,064   ... 3,042    ...
12	Rough bar. il/% in. diam ...........	i 132 in.	.125 in.	3,708	3,686   ......
13	Turned bar. il/% in. diam.	1.139 in.	.150 in.	3,320	3,258   ......
Test bars, Table 44, were furnished by Builders' Iron Foundry, Providence, R. I. Tested by Thomas D. West, at the works of the T. D. West Foundry Co , Sharpsville, Pa., Sept. i8th, 1894. Witnesses, Geo. H. Boyd andG. M. Mcllvain.
The first series of tests we will present is that recording the strongest mixture, seen in Table 89; the
* By a study of Chapter LXL. it will be seen that the inner column referred to above is obtained by a rule that cannot be recommended for j^-inch bars; and while that used for the outside column is preferable, it would be still more satisfactory if it were known that the %-inch bars did never vary from the size of their pattern —something which it is not practical to expectatio of 7.7 iron to i coke, in onler to deliver the melted iron in the same condition as on an ordinary day. In other words, an additional fuel consumption <>!' a little over 3,h per cent, is needed under the above conditions......................    3,658 units                            £