Royal Institution of Great Britain, 179 



A carriage intended to convey passengers, and not the mail, may 

 be made on the same plan, but the proportions of the several parts 

 will be different. 



Cwt8. Qm, Lba. 



Reservoir, containing 140 cubic feet 26 2 



Machinery .... 



Carriage .... 



Condensed air . . . 



Engineer and guard 



20 Passengers, with their luggage . 



84 

 The rate of travelling should be at the least ten miles per hour ; 

 the expenditure of air will be 4000 cubic feet, the reservoir will 

 contain 6000 cubic feet. It should be observed, that in bad 

 weather the reservoir may be charged with more air than the quan- 

 tity above mentioned. The expense of compressing the air will 

 vary with the cost of the power employed in condensing it, and the 

 quality of the machinery ; but, in general terms, it may be stated 

 that the power of steam produced by the combustion of one bushel 

 of coals will condense 2000 cubic feet of air, under a pressure of 

 36 atmospheres, or of 36 times 15 lbs. per square inch. 



To conclude ; on roads of great traffic, the capital invested at 

 present in horses and carriages will be sufficient to erect stationary 

 engines and condensing machinery, and also to construct the loco- 

 motive carriages ; and, in some cases, the capital required by the 

 proposed plans will be less than that which is now employed. 



Some clever little instruments intended to give facilities in nau- 

 tical surveying were laid upon the library-table by Captain Grover ; 

 and amongst them, one intended to lay a boat between two given 

 objects, in which, as in the camera lucida, one half of the eye was 

 occupied in looking forward, whilst, by means of a reflector, the 

 other half was looking directly backward. 



February bth. 



Mr. Burnett, on the oak, and especially the naval oak, of Great 

 Britain. — This subject being far too extensive to be fully enter- 

 tained at a single meeting, he selected some few practical points, 

 which most needed the exhibition of specimens and experiments 

 for their illustration, and contented himself with referring for other 

 information, which might as well be acquired in the study as in 



N 2 



