WATER-BELLOWS. 



>iir feet in height : it was a plain cylindrical tube, vrithoiit 

 ..iiy throat or funnel. But he found, when the water accu- 

 lately fdled the feftion of the orifice, and all the lateral 

 openings of the pipe were clofed, the pipe no longer emitted 

 any wind. 



According to this writer, the circumftances which favour 

 the moll abundant produftion of wind are as follows : — The 

 reparation of the defcending balls is more rapid in the upper 

 than in the lower part of the fall. In order, therefore, to 

 obtain the greateft effeft from the acceleration of gravity, 

 t is neceffary that the water Ihould begin to fall at the orifice 

 of the vertical tube with the lead poffible velocity, and that 

 the depth of the water in the horizontal trough (hould be 

 no more than is neceffary to fill the feftion of the vertical 

 tube. The vertical velocity of this feftion is fuppofed to 

 be produced by a height or head of water in the trough, of 

 a depth equal to the diameter of the tube. 



We do not know by direft experiment the diftance to 

 which the lateral communication of motion between water 

 and air can extend itfelf, but we may with confidence affume 

 that it can take place in a vertical tube, whofe feftion is 

 double that of the original feftion with which the water flows 

 from the trough into the pipe. Let us then fuppofe the 

 fedlion of the pipe to be double the feftion of the water in 

 the trough, and in order that the ftream of water may ex- 

 tend and divide itfelf through the whole double feftion of 

 tlie pipe, fome bars, or a grate, are placed in the orifice of 

 the vertical tube, to diftribute and fcatter the water through 

 the whole internal part thereof. 



Since the air is required to move in the blowing-pipe with 

 z. certain velocity, it muft be compreffed in the receiver. 

 This comprelfion will be proportioned to the funi of the 

 accelerations which (hall have been deftroyed in the inferior 

 and clofe part of the vertical pipe, that is, the part beneath 

 the vent-holes. Taking this clofed part of the pipe i^ foot, 

 we (hall have a preffure fufficient to give the requifite velo- 

 city in the air-pipe. The fides of this portion of th.e pipe, 

 as v/ell as thofe of the receiver, muft be exaftly clofed in 

 every part, to prevent the efcape of the air. 



The lateral openings in the upper part of the pipe may 

 be fo difpofed and multiplied, particularly towards the top, 

 that the air may have free accefs within the tube. 



In fome machines of this kind, the conftruftors feem to 

 have been of opinion, that a great height was required in the 

 water-fall ; but Dr. Lewis, who made a great number of 

 experiments upon the fubjeft, {hews that an increafe in 

 height can never make up for a deficiency in the quantity of 

 water ; four or five feet, he thinks, is a fufficient height for 

 the water to fall : and where there is a greater height, it 

 may be rendered ufeful by joining two or more machines 

 together in fuch manner, that when the water has once com- 

 mitted its air in the condenfing czik. or veffel, it ftiall flow 

 out into a new refervoir, and from thence defcend through an- 

 other funnel and cylinder, and fall from it into a condenfing 

 veffel, where the air is extricated and carried off through 

 the air-pipe. 



Another kind of water-bellows was invented by the in- 

 genious Martin Triewald, of Sweden, and is defcribed in 

 the Philofophical Tranfaftions. The machine confifts of two 

 caflts or tuns open at bottom, and fo loaded, that they will 

 fink into water in the fame manner as diving-bells. Thefe 

 being fo fufpended that they can be alternately lowered 

 down into water and drawn up again, will by proper valves 

 and pipes afford a continual blaft of air. 



Fig. 15. Plate Water-ivorks, reprefents thefe water-bellows 

 in profile. A A are two caflis, made nearly the fame ftiape 

 as diving-bells, being in the form of a truncated cone, or 



wider below than at top, where they are furnifhed with 

 clofe heads B B, but at the lower ends A A are quite open. 

 In the heads B B are valves V, which open inwardly, 

 and are made hke the palates of other bellows, with their 

 hinges and the valves themfelves covered with hatters' - 

 felt. They are caufed to fhut by eafy fteel fprings till the 

 air from above opens them, which happens only when the 

 bellows receive their motion upwards. The valves are fliut 

 by means of the preffure of the air within, when they fink 

 down into the water. 



On the fame heads two phable leather tubes R R are 

 fixed, one at the top at each water-bellows, which tubes are 

 made and prepared in the fame manner as thofe ufed in 

 water-engines for extinguifhing of fire, Thefe leathern 

 tubes or pipes reach from the bellows to the tubes T T, 

 which carry the wind into the furnace, or any other place, 

 according to pleafure. 



Thefe two bellows are fufpended from the lever by iron 

 chains K K, which are fattened to two fweeps S S, by which 

 means they hang perpendicular from the balance-beam, and 

 at the fame diftance from the centre of its motion C on the 

 oppofite fides. On the top of this balance-beam are fixed 

 two Hoping gutters F F, into which the ftream of water runs 

 from the gutter G, and gives motion to the whole work, 

 performing the fame fervice as an overftiot or any other 

 water-wheel ; but they coft much lefs, and give as even and 

 regular motion as a pendulum, for as foonias fo much water 

 runs*into either of the inclined planes of the gutters F F, 

 that the weight of the water exceeds the fri£lion near the 

 centre of motion C, and the weight of that bellows which 

 is funk down into the water, the gutter immediately de- 

 fcends with an incrcafing velocity till the balance meets with 

 the refiftance of the v/ooden fprings H H ; during tliis time 

 it has raifed the oppofite water-bellows, or that bellows 

 which is fixed under the oppofite gutter, the gutter 

 which has been filled being come down to the fpring H, 

 delivers all the water it has received, and at the fame time 

 the water begins to run into the oppofite gutter, which re- 

 ceives its load of water almoft as foon as the former is emp- 

 tied, fo that one of the gutters begins its effeft as foon as 

 the other has finilhed, and this continues alternately as long 

 as the ftream of water is fupplied. Thefe Hoping gutters 

 upon the balance-lever, therefore, perform all the effedl 

 which a water-wheel does in working the ordinary bellows, 

 and by means of the fame power of defcending water, but 

 ailing reciprocally on oppofite ends of the balance-beam. 



Thefe water-bellows blow the fire on the fame principle, 

 which produce the effeft of the ordinary bellows, •viz.. that 

 the air which enters the bellows, and which they contain 

 when the top is raifed, is again compreffed or forced into a 

 narrower fpace when the bellows clofe ; and fince air like 

 all other fluids moves to that place where it meets with the 

 leaft refiftance, it muft confequently go through the opening 

 which is left for it, with a velocity proportioned to the force 

 by which the air is compreffed, and muft blow ftronger or 

 weaker in proportion to the velocity with which the top 

 and bottom of the bellows are made to approach each other ; 

 the blaft alfo will laft a time proportioned to the quantity 

 of air that was drawn into the bellows through the valve or 

 pallet. 



The fame operation takes place in the water-bellows, for 

 the air which they contain muft neceffarily be compreffed 

 by the water, which rifes alternately into the bellows A A, 

 and obliges the air to go through the leathern tubes R R,. 

 as being the place where the air meets with the leaft re- 

 fiftance. 



In this machine, the chief part of the weight to be 

 T 2 ,' moved 



