Lieut. -Colonel A. Strange on Aluminium Bronze. 509 



i & 



possible in masses the transportation of which, over the most 

 difficult ground, should not be beyond the power of human 

 labour. 



" When on the point of compromising the difficulty by sepa- 

 rating, so as to form distinct packages, parts hitherto regarded 

 as inseparable, my attention was attracted by the various articles 

 made of f Aluminium Bronze ; sent to the International Exhibi- 

 tion by Messrs. Bell Brothers, of Newcastle, and M. Morin, of 

 Paris. The inquiries I made in various quarters satisfied me that 

 this metal possessed most valuable qualities, but I failed in my 

 endeavours to obtain reliable numerical data for comparing it 

 with other metals. T therefore instituted experiments on it, the 

 results of which I beg now to communicate to the Society. 



<e The alloy called aluminium bronze was first, I believe, made 

 by Dr. Percy five or six years ago, and is composed of aluminium 

 and copper in various proportions, 10 per cent, of aluminium, 

 however, giving the best material for mechanical purposes. 



" The qualities of most importance in instrument-making are, 

 (1) tensile strength; (2) resistance to compression; (3) mal- 

 leability ; (4) transverse strength or rigidity ; (5) expansive 

 ratio ; (6) founding-qualities ; (7) behaviour under files, cutting- 

 tools, &c. ; (8) resistance to atmospheric influences ; (9) fitness 

 to receive graduation; (10) elasticity; (11) fitness for being 

 made into tubes ; (12) specific gravity. 



" Of these, tensile strength, resistance to compression, and 

 malleability were most obligingly tested forme by Mr. Anderson 

 at the Royal Gun Factory, Woolwich ; and the other qualities by 

 Messrs. Simms, by whom the great theodolite is now being con- 

 structed. I will take the above enumerated properties in then- 

 order, premising that to have obtained results of an absolute and 

 final character would have involved more time than I could 

 spare, and that therefore those which follow, though sufficiently 

 reliable for almost any practical purpose, are open to the correc- 

 tion of more extensive experiments. 



" (1) Tensile strength. — This was tried some years ago by Mr. 

 Anderson with the following results. Breaking-strain, 



Aluminium bronze . . 95,7471 1U . , 



Gun-metal 33)000 jibs, per square inch. 



Mr. Anderson was good enough to try it again for me in Sep- 

 tember last, and states in his report, l The average tenacity of 

 this metal proved to be 22 tons 12 cwt. (50,624 lbs.) breaking- 

 weight per square inch in the two specimens tested; elongations 

 did not take place until 4300 lbs. in the one case, and 3600 lbs. 

 in the other, had been applied, when a permanent elongation was 

 noticed of *009 of an inch in the first specimen, and '034 of an 



