510 Lieut. -Colonel A. Stranse on Aluminium Bronze. 



r x 



inch in the last/ Mr. Anderson adds that the specimens were 

 not quite sound. 



" In the above-cited report Mr. Anderson gives a higher ten- 

 sile strength to gun-metal than before, namely, 17 tons (38,080 

 lbs.) for the average of the ' best specimens' tested at the gun- 

 factories. 



" Combining the results, we have the average breaking tensile 

 strength of the two metals as follows : — 



n i. 95747 + 50624 „ Q1CK 

 Aluminium bronze - = 7o,lo5 



32000 + 38080 QK Mn f lbs - P er "»■ inch ' 



(jrun-metal . . . = = o5,040 



the ratio being 1 to 0*48, or rather more than 2 to 1, in favour 

 of aluminium bronze. 



" For the purpose of comparing the tenacity of the new alloy 

 with steel, we have data given by Mr. Anderson in a lecture* on 

 Materials for Rifled Cannon, in which he states that cast steel 

 varies in tensile strength from 114,000 to 67,000 lbs. per square 

 inch; but he objects to the higher qualities as liable to brittle- 

 ness, and prefers, where great strains are in question, an average 

 quality of cast steel breaking at 80,000 lbs. ; and he adds that 

 specimens from a gun made of Krupp's famous cast steel, cha- 

 racterized by ' softness ' (which Mr. Anderson considers favour- 

 able to tenacity) and e perfect soundness/ gave 72,000 lbs. per 

 square inch, which we see is 1185 lbs. less than the average 

 strength of aluminium bronze above given. 



" (2) Resistance to Compression. — Mr. Anderson reports on 

 this as follows : — 



" ' The ultimate amount of compression applied was 59 tons 

 2 cwt. 1 qr. 4 lbs. (132,416 lbs.), under which the specimen f 

 became too much distorted to permit of more weight being 

 applied with any true result. Compression was not perceptible 

 until 9 tons 2 cwt. per square inch (20,384 lbs.) was applied, 

 when the specimen suddenly gave to the extent of *006 of an 

 inch, and on the weight being removed an elasticity of '001 was 

 observed, which gives the first permanent compression as *005 

 of an inch/ 



"The compressive strength of cast iron varies a good deal. 

 That of f Carron Iron, No. 3/ the highest given in Ure's ( Dic- 

 tionary of the Arts/ is 115,542 lbs. per square inch ; but it is 

 difficult to compare in this respect two metals whose behaviour 



* Published in No. XXIII. Journal, Royal United Service Institution. 



t "The specimen subjected to this enormous pressure, distorted though 

 it is, does not exhibit the trace of a fissure. The cohesion of its particles 

 is inviolate." 



