648 TRANSACTIONS OF SECTION G. 



influence of exposure to London atmosphere a specimen of each alloy has been 

 placed on the roof of King's College, London. All the specimens are in the 

 form of wire 0'126 inch (3'2 mm.) diameter. 



Commercial Aluminium. — A specimen has steadily increased its electrical 

 resistance to 17-2 per cent, in thirteen years. Copper.— It has already been 

 pointed out that the electrical resistance of the copper series in a given time 

 increases with the percentage of copper. One specimen containing' 2'61 per 

 cent, of copper had so far corroded in 1911 that it broke quite easily. Another 

 specimen containing 1-86 per cent, of copper has now so far corroded as to 

 become practically useless as an electrical conductor. The tests emphasise the 

 opinion already expressed that alloying commercial aluminium with copper 

 except in small quantity is not to be recommended. Copper-Manganese. — 

 Three alloys containing from 0-02 to 0-09 Cu and 0-05 to 1"78 Mn have steadily 

 increased their electrical resistance to about 10 per cent, in fourteen years. 

 The specimen with the highest percentage has a breaking load of 35,000 lb., 

 and is apparently in good condition. Copper-Nickel. — A specimen containing 

 108 per cent. Cu and 1-29 per cent. Ni has somewhat diminished its electrical 

 resistance — the percentage being now 12-4, as against 194 in 1908. Its breaking 

 load was 45,900 lb. before exposure. Copjier- Zinc- Nick el. — One specimen con- 

 taining 0-11 Cu, 1-77 Zn, 2'01 Ni, has diminished its electrical resistance as 

 shown by the following figures : 



Year 1901 .. 1903 .. 1904 .. 1908 .. 1911 .. 1913 .. 1915 

 962 .. 995 .. 1013 .. 1285 .. 1125 .. 1102 .. 1102 



Copper-Manganese-Magnesium,. — The alloy known as ' Duralumin ' is stated 

 to contain about 0-5 Mg, 3-5 to 55 Cu, 0'5 to 0-8 Mn. A breaking load as high 

 as 90,000 lb. can be obtained according to treatment. The specimen exposed 

 has steadily increased its resistance to 9-6 per cent, in four years. It is, how- 

 ever, so brittle that a small loop cannot be bent without fracture. 



The author was unfortunately imable to report on the copper specimen, as it 

 had been stolen from the roof. 



SATURDAY, SEPTEMBER 11. 

 The following Papers and Report were read : — 



1. Recent Improvements in the Traction of Vehicles. 

 By T. H. Beigg. 



The author for more than a quarter of a century has made his life-study the 

 subject of mechanical forces relative to traction, and has applied these principles 

 to various contrivances, such as shaft-supporting appliances, the ' Ply well ' for 

 poled-vehicles, and other mechanical contrivances. Recently the War Office 

 placed at his disposal the drawings of artillery and general service wagons in 

 order to give him an opportunity of showing how the draught of these vehicles 

 could be improved. His attention also having been directed to the machine- 

 gun, he has devised a means by which these weapons can be more rapidly trans- 

 ported, and manipulated with greater ease to the gunners and with more deadly 

 effect upon the enemy, while at the same time both gun and gunners are pro- 

 tected by armour-plate. His paper is a description of the new mechanical 

 appliances which he has devised as a result of the above opportunity. 



The salient feature involved in the easy haulage of artillery and limber- 

 coapled ammunition and general service wagons is precisely the same for 

 civil as for military ' purposes ; and it remains the same regardless of whether 

 traction be effected by men or by horses. It will be found upon investigation 

 that conditions which conduce to the greatest comfort and efficiency in the 

 transport of man by his own muscular effort are identical with those which 

 conduce to the comfort and efficiency of transport by horses and other living 

 creatures, an illustration of which are the mechanical movements of the swan, 

 which are effective in producing the least possible rise and fall of its body with 

 the greatest possible thrust in the desired direction of motion — a movement not 

 hitherto described, 



