288 Progress in Science. [April, 



■ « 



excellent paper on this subject recently published by Professor T. Rupert 

 Jones.* 



MINING. 



A new self-extinguishing safety-lamp has been devised by Mr. W. Simpson, 

 of Battersea. It is constructed for burning paraffin oil, so that the collier may 

 be furnished with a more brilliant light than usual, and therefore be less dis- 

 posed to remove the wire cage. Any attempt to do this, however, will imme- 

 diately bring into play the automatic extinguisher. This consists simply of 

 two small metal plates, which are caused to fall upon the wick and wick- 

 holder by means of a spring that is released on unscrewing the cage from the 

 body of the lamp. 



Attention has also been lately directed to the magnetic lock applied to the 

 safety-lamp some short time ago by Mr. S. P. Bidder, jun. In this lamp the 

 bolt of the lock can only be withdrawn by the action of a powerful magnet, and 

 a strong electro-magnet is, therefore, permanently fixed in the lamp cabin. As 

 an instrument of the requisite strength could not be carried about, it appears 

 that the illegitimate opening of the lamp is placed beyond the power of the 

 working collier. 



A simple form of safety apparatus for preventing accidents in shafts from 

 breakage of the ropes or from over-winding, has been invented by Messrs. 

 Turner, Grey, and Brydon, of Barrow-in-Furness. As in many other forms of 

 safety machinery, the cage is sustained in its descent by the action of chisel- 

 pointed pawls which are caused to clutch the wooden guides. These catches 

 are connected by means of levers with a bar which passes through a vertical 

 cylinder fitted with india-rubber springs, and is attached at its other end to the 

 rope. In the ordinary action of the cage the springs are retained in a state of 

 contraction, and the clutches glide freely up and down quite clear of the guide- 

 rods ; but on rupture of the rope the springs expand and the clutches are 

 brought into play. In favour of this apparatus, it may be said that the safety 

 arrangement comes into action every time the skip completes its journey up cr 

 down the shaft; and being, therefore, in constant use, there is no fear of its 

 being out of order at the fatal moment when an accident occurs. 



To obviate the inconvenience of having the apparatus which develops the 

 motive power connected directly with the cutting-tool, Mr. George Simpson has 

 invented coal-cutting machinery by which the moving power may be long 

 retained in one position, whilst the tool alone moves with the advance of the 

 work. Different forms of cutter for excavating the fuel are employed ; but it 

 would be difficult to describe the mechanical details without the aid of 

 diagrams. They may all, however, be brought into relation with the apparatus 

 for developing motive force — which may be steam, compressed air, or manual 

 labour — by means of pulleys and belts, or other modes of transmitting motion. 



METALLURGY. 



It is matter of familiar observation that certain metals — especially iron and 

 steel — are more readily broken in cold than in warm weather. The incon- 

 venience arising from this apparent increase in brittleness is especially felt by 

 the railway engineer, who well knows that more accidents occur from fracture 

 of rails, tyres, and axles in winter than in summer, or in a severe climate than 

 in a mild one. But while none will probably deny this fact, opinion is strangely 

 divided as to its explanation. On the one hand it is affirmed that the tenacity 

 of the metal is actually lowered by a reduction of temperature ; and this seems 

 to be the common opinion entertained by practical men, who constantly speak 

 of iron becoming brittle when "the frost is in it." On the other hand, there 

 are not wanting many eminent men of science who maintain that the strength 

 of the metal is not reduced by lowering the temperature ; it is true, they admit, 

 that a rail, for example, is broken more readily during frost, but this is not 

 because the metal is really more brittle, but simply because the road on which 



* Geological Magazine, Feb., 1S71. 



