340 Proceedings of the British Association for 1850. 



in were thrown into the eye thus placed, as in the New- 

 tonian telescope at the side. The advantage from this ele- 

 gant arrangement is, that the eye does not require to move 

 upon a movement of the telescope. Mr Nasmyth then de- 

 scribed his plan of casting specula, by which all unsound- 

 ness was avoided. 



Mr Lassell, to whom so much is due in the polishing of 

 specula, observed, that if Mr Nasmyth could give an equa- 

 torial movement, his instrument, he thought, would be per- 

 fect. 



Dr Robinson observed, that if any mechanical arrange- 

 ment were desired, and this was certainly one, he had no doubt 

 that in Manchester could be found the men to achieve it. 



Professor Smyth then gave an account of a new form of 

 equatorial at present constructing for the Edinburgh Obser- 

 vatory, and a folding dome for extra meridian instruments. 

 Professor Smyth in another communication explained a 

 mode of cooling the air in tropical climates. This was, 

 in the first instance, to condense air by mechanical means. 

 Then to allow -the air thus condensed, and consequently 

 heated, to fall to the common temperature. The condensed 

 air thus let loose, and allowed to flow into a room, would, 

 by its expansion, lower all the air with which it comes in 

 contact. He had tested the principle on a large scale, and 

 found it to answer his expectations. 



Mr Taylor knew of men working in one of the Cornwall 

 mines at a temperature of 110°. It would now be possible 

 to send them down a treat of cold air. 



Mr Rankin e said, — In reference to the power required, 

 that he had made the calculation, and the result was, that 

 one horse working for one hour lowers 9000 cubic feet of air 

 20° ; and, of course, in this proportion for all other cases. 

 This was exclusive of friction. 



Mr Appold then explained the arrangements in his hydra- 

 metric instrument for regulating the atmospheric moisture 

 of houses, which seemed to answer well. 



Mr Sykes Ward gave an account of his improved gas 

 stove. 



