VOL. XLll] PHILOSOPHICAL TRAfJSACTIONS. 345 



will still remain a great contact in the particles, and the points of equilibrium 

 for breaking, viz. o, e, above, and t, c, below, will be removed nearer to the poles 

 n, or s, than when the particles are round ; the consequence of which will be^ 

 that the spring must be bent much further, to be in danger of breaking, than 

 in the former supposition ; as may be seen in fig. 15, where two particles being 

 opened about the point d as a centre, the attracting points c, c, and S, i, have 

 still some force to help to bring back the particles to their whole contact ; be- 

 cause, in this shape of the particle, the attracting points c, c, S, S, are removed 

 only in proportion to their distance from the angular point d ; whereas if the 

 particles had been spherical, and the line d S an arc of a circle, the attracting 

 points c, c, and i, i. would have removed from one another further than in pro. 

 portion to twice the square of the distance from d, as in fig. 11, and so have 

 afforded very little help for bringing back the particles to their contact. A row 

 of particles in the spring thus conditioned, is to be seen in the natural state at 

 BA, fig. 1 6, and bent at ba in the same figure. Here it is to be observed, that 

 if, in this figure of the particles, you would bend the spring to bring the par- 

 ticles to touch at their point of breaking equilibrium, you must open them so 

 much on the contrary side, that the spring will be bent far beyond any uses in- 

 tended to be made of it, as appears by fig. 17, where two particles are brought 

 to touch at the equilibrating point e; and by fig. 18, where many particles 

 being put into that condition, the spring is brought round quite into a 

 circle. 



Now the common practice in making springs, is the most likely to produce 

 this effect required in the particles; for the hard spring, whose particles were 

 round,, or nearly so, is heated anew, and while cooling gently, the mutual 

 attraction increases tlie contact, so that the particles grow flatter in those places 

 where before they had but a small contact; and lest this contact should become 

 too great, the spring's softening is stopped by quenching it in water, or oil, 

 or grease. Another way of making springs, is to begin and shape them in 

 cold unelastic steel, and then having heated them to a small degree, for ex- 

 ample, to a blood red heat, immediately to cool them in some proper liquors. 

 This also settles the particles in their oblong figure, through which they must 

 pass before they become round, or nearly so, in a white heat. That particles 

 of steel are fixed in the figures which they have at the instant of dipping, will 

 not appear strange, when we consider, that dipping red-hot steel in cold 

 liquors, in a particular position, makes it magnetical. If it be asked, how we 

 account for making springs only with hammering, it is easily answered, that 

 we can make iron and steel magnetical only with hammering; and if we can 

 give and destroy poles in the whole piece, there is no improbability to think 



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