106 REPORT — 1841. 



a constant in-draught of atmospheric air will be ensured, sufficient to obviate the evil. 

 The heat evolved by the perfect combustion of this inflammable gas, under these cir- 

 cumstances, will, he says, more than compensate for the admission of cold air into 

 the upper part of the stove. The perforations just mentioned will also obviate, in a 

 great measure, the want of ventilation. The author described a small rarefying ap- 

 paratus, to be inserted in the vertical shaft connected with a descending flue, in which 

 apparatus a small culm fire is to be constantly kept. The expense of this is not more 

 than one penny per day ; and Mr. Hearder has found by experience that the draught 

 produced by this means is so powerful as to ensure the success of an underground 

 flue several hundreds of feet in length. 



On the Water Poioer at Wheal Friendship Mine. 5y John Taylor, i^.iJ./S'. 



On the present state of the Thames Tunnel. By Sir Isambard Brunel. 



Mr. Whitworth gave an account of ' A New Construction of Die Stock for Cutting 

 Screws.' 



Mr. D. Laing explained ' Smith's Wire Ropes.' 



Mr. Brockedon explained his ' Application of Caoutchouc as a Stopper for Bottles 

 containing Liquids.' 



