130 Mh. W. M. Buchanan's Theory of the Reaction Water- Wheel 



is therefore not probable that the maximum effect was obtained. A 

 smaller model, still in my possession, yields as a maximum, under like 

 circumstance, p v = 79873 W H. 



Literal References to the Drawings, Plates III. and IV. 



The same letters indicate the same or corresponding parts in all the 



Drawings. 



a, the machine ; and b its vertical spindle. 



c, the water-joint, formed by the coincidence of the edge of the central 

 opening in the machine with that of the rising-ring d. 



e, the collar-ring, bolted upon the foundation flange of the supply-pipe f. 



g, saucer-shaped disc, to take off a part of the hydrostatic pressure, and 

 forming a water-tight joint with the upper plate of the machine. 



A, waste-pipe, to convey the water escaping into the hollow disc g, into 

 the atmosphere. 



?, traversing-rod of the governing apparatus. 



h, vanes on the extremities of the same. 



I, endless-screws on the rod i, connecting the wheels m with the eccen- 

 trics n, inside of the valves. 



p, q, parallel-cheeks, between which the valves slide. 



r, spiral-spring on traversing-rod i. 



s, indices, for height of fall and quantity of water in the cistern u. 



t, reservoir for applying the experimental apparatus with water. 



u, cistern, into which the water discharged by the machine is delivered. 



v, pulley for the friction-brake, used to test the power of the machine. 



w, clack-valve in the bottom of the water-course, between the machine 

 and the cistern u. 



x, culvert for waste water. 



y, handle of the valve for emptying the cistern u. 



z, float in the reservoir, attached to the head-valve and scale of fall s. 



15th April, 1846. — The President in the Chair. 



Br. R. D. Thomson presented an additional donation of plants, from 

 Northern India, collected by Dr. Thomas Thomson, junior, for which the 

 thanks of the Society were voted. The Council reported that Mr. Liddell 

 had intimated to the meeting of this evening, that the town Council had 

 agreed to the Report of the Joint Committee of the Town Council and 

 the Society, as to the exhibition of models — an important provision being, 

 " that the Philosophical Society guarantee against loss, in equal propor- 

 tion with the Town Council, to the extent of £100 ; and that if the loss 

 should exceed this sum, the excess to be borne exclusively by the Town 

 Council, provided that the gross expenditure shcill not exceed £500." 



