394 Mr. Mallet on the Physical Conditions 



Specimens marked Nos. 1 , 2, and 3, were cut from a " runner" of a cast, of a 24-poun- 

 der howitzer, thus: — 



B A 



X ... 12" ... X ... 4" ... X ... 3 ft. 6 in. ... x ... 4" ... x ... 3 ft. 6 in. ... x 4" ... x ... 12" x 

 No. 1. No. 2. No. 3. 



A is the upper and B the lower end of the cylindric " runner," which was 2i inches 

 diameter. The runner, of course, stood vertically in the mould when being poured. 



The centre of each piece, Nos. 1, 2, and 3, was turned into a (solid) cylinder, 1 inch 

 in length and 0'5-inch diameter, A, B, C. 



Composition of the metal used for charging the furnace in the casting of the gun : — 



Cwt. qrs. lbs. 



Head, .... 13 3 22 

 Copper pigs, . . 25 1 4 

 Hard metal, . . 2 8 (half copper and half tin.) 



The amount of compression was noted after each 2500 lbs. pressure, as given in the 

 Table. 



The testing was discontinued when the axis of the specimen became oblique to the pres- 

 sure. This occurred in all the specimens, probably from the smallness of the base, or want 

 of homogeneity in the composition (want of the line of pressure remaining perfectly inva- 

 riable?— R. M.) 



The power of the testing machine is limited to the greatest pressure given in the 

 Table. 



Specimens No. 4 were cylinders taken from the cascable of a 24-pounder howitzer, 

 and divided into — A the top, B the centre, and C the bottom, cast under the pressure, 

 including the " dead head," of about 10 feet. 



The time occupied in obtaining the results averaged two minutes for each 2500 lbs. 



