70 Mayow 



For let any combustible material which will readily 

 take fire be suspended in an inverted cupping-glass as 

 large as can be had, as is shown in Plate V., Fig. i (I am 

 myself in the habit of suspending a bit of camphor to 

 which a small piece of linen, charred in the usual way 

 into tinder and dipped in melted sulphur, is attached). 

 When this has been done, let the inverted cupping- 

 glass be immersed in the water about ten finger- 

 breadths so that the water enclosed in the glass may 

 be at the same level as the water outside, which can be 

 done, easily enough, by means of the bent syphon 

 already described ; and lastly, let the water outside be 

 drawn oflF until the level of the water within is higher 

 than that of the water outside, so that it may be more 

 distinctly seen, or better, let the cupping-glass be trans- 

 ferred to another and shallower vessel by placing 

 under it a small vessel, big enough, however, to receive 

 the mouth of the cupping-glass, and then transferring 

 the small vessel filled with water, together with the 

 cupping-glass resting upon it, into a suitable vessel 

 almost full of water. And let the cupping-glass remain 

 there until the air heated by the hands of the operator 

 has been condensed to its original state. And then, 

 lastly, let the height of the water within be noted by 

 papers affixed here and there to the sides of the 

 glass by means of a paste made of barley-meal boiled 

 in water. Now let the cupping-glass be exposed to 

 the rays of the sun and let the camphor or other com- 

 bustible matter enclosed in it be kindled by means of 

 a burning-glass, by first lighting the aforesaid sulphured 

 linen placed under the combustible matter. When this 

 has been done you will see the water within descend on 

 account of the agitation of the fiery particles, and the 

 rarefaction of the air inside. When the light has gone 

 out let the cupping-glass and the small vessel on which 



