Scientific Intelligence. — Arts. 195 



lion by the introduction of this principle: 1. The total absence 

 of all smoke ; 2. The dispensing with the chimney ; 3. A saving 

 of at least 120 per cent, in the cost of fuel, and SO per cent, in 

 the space to stow it ; -k A saving of about 400 per cent, in the 

 space occupied by the boilers. The same principle is now ap- 

 plying, by Messrs Braithwaite and Ericsson, to the new loco- 

 motive engines constructing for the Liverpool and Manchester 

 railway, wliich are to be delivered at mid-summer ; and a simi- 

 lar combination of vast power, in a small space, with a great 

 saving of fuel, will be applied to them. 



Memm-anda relative to the Experiments made at Mr Laird's ivorks at North 

 Birkenhead, with the new Low Pressure Boiler, on the exhausting principle of 

 Messrs Braithicaite and Ericsson, by Alexander Nimmo, C.E. Dublin, and Charles 



B. Viffnoles, C. E. London The exhausting apparatus consisted of a fan- 



wheel, with broad radial leaves, revolving within a close box or chamber, 

 placed a little apart from the boiler, but connected with it by a passage lead- 

 ing from the flues traversing the boiler : a short tube above the exhausting 

 chamber passed out to the atmosphere. The furnace was attached to and 

 placed at the end of the boiler, opposite to the exhausting apparatus, which 

 latter being put to work, drew through all the turns of the boiler the hot air 

 from the fire, which passed over the throat of the furnace through the bridge 

 flue, and then successively through the other five turns of the flue arranged 

 through the boiler, and finally was drawn through the exhausting chamber 

 and passed into the atmosphere. The heat, which in the furnace was ex- 

 tremely intense, was absorbed by the water in the boiler as the air rushed 

 through the flues, and, when passing up the tube or funnel from the exhaust- 

 ing chamber, was so far cooled that the hand or arm might be placed with 

 impunity down the tube, the temperature probably not exceeding 180" of 

 Fahrenheit. Not the slightest smoke was perceptible. The following are 

 the principal dimensions measured : 



Ft. In. Ft. In. 



(20 deep I ( ' ^ "^^^P 



Furnace -J 2 C long Ash Pit ^ 2 G long 



2 6 wide I 2 6 wide 



The openings of the fire bear 

 equal to about half the area 

 of the bottom. 



Ft. In. Ft In. 



„ , ^. (2 6 high 1 n 4.■^ I Diameter of Exhaustmg 

 Exhausting J 3 g ^^r, J Outside ^^j,^^, ^g „ 



Chamber |^ 3 g j^^^ j^ Dimensions | jj^eadth of the same, . . 10 

 Bridge flue or throat from the furnace 2 feet 6 inches broad, 4 inches wide, 

 2 feet deep. 5-16th inch iron plate. 



First turn of the flue 4 inches wide, 2 feet deep, ) ,,|j j^j^j^ -^^.^^ plates. 



2d, 3d, 4th, and 5th turns, 3 inches wide, 2 feet deep, / " 



Whole length of the flues through the boiler, ... 45 feet- 

 Superficial area of the heating surface, .... 247' square feet. 

 The contents of the water in the boiler when filled were 



from 85 to 90 cubic feet. 



The superficis^l area of the evaporating surface in the boiler, 33 square feet. 



