G.— ENGINEERING. 129 
of Thornycroft and Yarrow are so honourably connected. The exceed- 
ingly high speeds attained taught naval architects much till then unknown. 
As a later development, the construction during the War of the coastal 
motor-boats was most instructive and was a notable contribution towards 
the final victory. 
There are now, besides the Government tank at Haslar, the following 
Froude tanks in this country in the order of age—Denny (Dumbarton), 
Brown (Clydebank), William Froude (Teddington), Vickers (St. Albans), 
and Parsons’ have also a smaller open-air tank at Newcastle: that is six ; 
and there are in Italy, Germany, France, Sweden, Russia, Austria, Japan, 
and the United States other eleven, a total of seventeen, and it may be 
claimed that tanks have had more far-reaching effect on design than any 
other means of research. 
And yet, when one considers the research carried out on ferrous and 
non-ferrous metals, that claim may be disputed. Time fails me to do more 
than indicate to you the history of mild steel. Great Britain was the birth- 
place of the steel industry and Sheffield was its cradle. Bessemer cupola 
and Siemens-Martin open-hearth steels were British inventions, and at 
one time this country held premier place in tons of steel produced per 
annum. It was on the Bessemer converter that America built up her vast 
steel industry, but in shipbuilding and marine engineering Siemens- 
Martin open-hearth steel was the key to success. While steel had been used 
in shipbuilding at an earlier date, our present material came into daily use 
in merchant-ship building in the late ’seventies of last century, and I can 
remember the interest taken in the Buenos Ayrean, the first steel Atlantic 
ship, built in 1879. Grave doubts were expressed as to the wisdom of 
Messrs. Allan in ordering that steamer, and when she developed certain 
infantile troubles and was dry-docked for the first time a crowd of talent 
_ examined her from stem to stern. At last one lynx-eyed surveyor found 
a crack in a bottom plate, but there was great relief when the superintend- 
_ Ing engineer removed the crack with the point of his knife: it was a hair 
from a paint-brush ! 
With the considerable reduction in scantlings allowed by the Classifi- 
cation Societies mild steel rapidly displaced iron in ship construction. 
But still we were warned that it was unreliable if worked at a blue heat, 
and some failures were recorded. Further improvement in manufacturing 
methods, however, finally gave us a material of great reliability and easily 
worked. The limits of 28-32 tensile strength and 20 per cent. extension 
in an 8-inch specimen have been standard now for many years, though 
steels of greater carbon content and higher tensile strength have been 
ised ; and as Young’s modulus is practically the same for all ordinary 
earbon steels, these higher tensile steels could be used in conjunction with 
milder steels without disadvantage. But there is now another mild carbon 
steel on the market which has a higher elastic limit, the use of which is 
just beginning ; 5 opin tS: claimed that it will ensure firthee advantageous 
EE a, 
Sir Robert Hadfield’s invention of ite -manganese steel gave a fresh 
‘im petus to research in ferrous alloys. Among other facts, he found that 
while 2 per cent. to 3 per cent. of manganese rendered carbon stee! so brittle 
as to be useless, when a 13 per cent. alloy was made and properly heat- 
treated a material resulted of extreme toughness and great resistance to 
1925 K 
