Scientific Intelligence. — Arts. 197 
engraver, that he should be obliged to give up the task of en- 
graving upon steel-plates, owing to the impossibility of finding 
any gravers capable of cutting them, without perpetually break- 
ing in the points, Mr T urrell hit upon the following method of 
accomplishing his object. He had formerly been much in the 
habit of seeing the singular manner in which the 'watch-spring 
makers in Clerkenwell treat the steel of which their springs are 
made. Pieces of steel- wire, of a proper quality and size, are 
spread by the hammer, when cold, into thin plates. After being 
brought to a certain thinness and width, they are hardened, and 
then tempered, over the flame of a spirit-lamp, to the spring-tem- 
per, or, as it is termed, the raven’s grey colour ; they are then sub- 
jected to the planishing and condensing action of the hammer, 
and being then brightened, are lastly blued over the flame of a 
spirit-lamp. Previous to their being blued , they had by the 
planishing, condensing, and polishing, apparently lost all their 
elasticity and hardness, and could be readily bent in any man- 
ner, and would afterwards remain so bent, as though they had 
never been hardened and tempered at all ; and yet, upon being 
blued , they regained all that elasticity for which they are so high- 
ly esteemed Mr Turrell, considering the above circumstance, 
thought, that, upon tempering a graver, though not to the de- 
gree used by the watch-spring makers, it might possibly be ren- 
dered capable of being acted upon by the blows of a hammer, 
so as to condense the pores of the steel, opened, as they must 
be, by the heat necessary in even the most careful hardening, 
but still more in the usual manner of making gravers in great 
numbers. He therefore tempered a graver to the straw-colour 
only, and had the satisfaction to find, that, on laying the back 
of it upon a rounded anvil, he could, by a repetition of gentle 
blows, with the flat cross pane of a small and very hard cast-steel 
watchmaker’s hammer, succeed in rounding or blunting the acute 
edge of the belly of it considerably, thus proving that it had un- 
dergone a great degree of condensation ; and upon again tem- 
pering it to a straw-colour, and grinding and whetting the edge 
to a proper shape, the graver readily cut the steel-plate, and con- 
tinued to do so, it being evidently also much toughened by this 
additional labour. He has since repeatedly succeeded in thus 
improving the quality of those Lancashire or Sheffield gravers 
