1825.] Mr. Whatton on a Safety Hood and Mouth-piece. 283 



secondly, it would prevent all danger from a sudden exposure of 

 the breast and neck (already in a state of profuse perspiration) 

 from a high temperature to cold air, caused by opening the 

 dress to loose the straps and buckles by which the machuie is 

 fastened round the shoulders and chest. 



The second alteration would be to insert a shallow oblong 

 concavo-convex glass, instead of the square and socket at pre- 

 sent in use ; by which the man would be enabled to see on all 

 sides with much less difficulty, and without any change of pos- 

 ture ; while, at the same time, refraction would be prevented by 

 the thinness of the medium, which cannot be the case with a 

 plano-convex glass, as by some gentleman has been recom- 

 mended. Over this sight-piece might also be advantageously 

 fixed a strong leather peak, to protect the eyes from the glaring 

 light of the fire, and the glass from injury by falling bodies, or 

 blows from above ; and in lieu of the simple water for the im- 

 mersion of the breathing funnel, a solution of caustic potash 

 might be substituted, which would neutralize the carbonic acid 

 gas and wood acid, suspended in the smoke (the contact of 

 which last is so severely painful to the eyes), and thereby, in a 

 still greater degree, effect the advantages for which the machine 

 is intended. 



In the experiments of Friday last, made before the President 

 and Directors of the Manchester Fire and Life Assurance Com- 

 pany, and a number of scientific gentlemen, the apartment in 

 which Roberts remained 24 minutes, at a temperature of 130° 

 Fahr. was a foundry drying oven, filled with smoke and vapour, 

 given off by the combustion of damp cotton, waste wet hay, and 

 sulphur, the least exposure to which produced intense smarting 

 in the eyes, and an excessive irritation on the lungs, and would 

 probably have destroyed life if it had been continued but for a 

 few minutes ;* while to a person wearing the apparatus nothing 

 more occurred than an acceleration of the action of the heart 

 from 70 to about 160 per minute, attended by a free perspiration 

 over the surface of the body ; with some sensation of exhaustion 

 and giddiness in those unaccustomed to the expermient. 



The chief excellence of Roberts's instrument is its simplicity; 

 for it can never be admitted that an invention however efficient 

 in the purposes for which it is intended, if it be complex in its 

 construction, and difficult in its application, can be at all com- 

 parable in value to one so plain in principle, and so intelligible 

 in its utility, as his is. 



It must iikewise be borne in mind that the machine is not 

 invented for scientific persons, or for those who are familiar 



• Ou subiiiittii!^ tills iiiived air to <'heniiccil analysis, it was found, in the several 

 fsperinients m Dr. Henry and Mr. Dalton, to bt- atmospheric air, charged with about 

 Dijc |)Ci- cent, of carbonic acid (jas, and de|)rivcd of a wrresjjondi'Ut volume of oxygen, 

 »nd ini|)re;^nattd with wootl acid and !><>'.nc c>scntial oil. 



