Scicntijic LitcUigcncc. —Mechanical Philosophy. 177 



ver, adapted to the deflection of light, he caused them, during then- 

 action upon the ray of light, to be successively heated to wliltcness, 

 and cooled to — 10^; but no change whatever was thereby pro- 

 duced upon the colored bands of deflected light- The metal was 

 then made to serve as conductors to currents of common electricity 

 from powerful batteries, strong enough to ignite and to melt them, 

 passed in either direction ; and a powerful magnet was also In one 

 case attached to tlie deflecting plate ; but in no case was there any 

 appreciable alteration In the light, nor was there any change when 

 the rays of light, prior to their arrival at the metallic edge, were 

 made to pass through vivid flame. 



t _ A' — — o 



The author infers from these facts, that the exj^lanation of deflec- 

 tion, founded on the influence of the attractive force, or the existence 

 of certain atmospheres heretofore attributed to the body, cannot be 

 admitted, since such a force or such atmospheres, subjected to agents 

 so fit to control them, produced no change in the phenomena. These 

 facts certainly do not establish the system of undulations, but tliey 

 may perhaps be considered as favoring it by ruining the only ex- 

 planation which stands opposed to it- But the author does not deny 

 the difficulties which arise from these experiments relative to die 

 theory of undulations ; and he asks why the motions of luminous 

 waves, which ought to be so regular, are not disturbed by the mo- 

 tion of subde fluids which dash against them in their march. He 

 refers the solution of these questions to that future point in science 

 when the nature of these agents shall be more intimately known. 

 ^nn. (Je Chimle, Aout, 1829. 



C. Preservation of firemen against fire and fiame. — Chevalier 

 AldinI, of Milan, a gentleman well known to science, has recently 

 ^i'ought into notice an equipment which appears to offer a remarka- 

 t>le protection to persons exposed, as firemen are, to excessive heat, 

 and which enables them to encounter with impunity dangers which 

 it would be very imprudent to hazard, without such a safeguard. 



This protection consists, 1st, of a covering composed of a tissue of 

 asbestus, a su1)stance somewhat in use among the ancients as the 

 material of an incombustible cloth. Chevalier AldinI has succeeded, 

 it appears, in preparing this substance in such a manner that It may 

 ^e spun and woven without an intermixture of cotton or other fibre : 

 2d, of one or more additional coverings of metallic or wire gauze — 

 of these materials, coverings are made adapted to the head, hands, 



V0L.XVIIL— No. 1. 23 



