356 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



cent. It is found that with the full service charge in large cannon, the 

 range with the same samples of powder is much more nearly uniform. 



The Chairman. — The products of the combustion of gunpowder burned 

 under different temperatures are entirely different, and as the temperature 

 varies with the pressure, the force exerted would be affected by the ease 

 with which the shot was moved. This fact suggests the great number of 

 elements which come into an experiment to determine the force of any par- 

 ticular sample of powder, and, consequently, the difficulty of making the 

 investigation. 



** Modes of Raising Water. 



The regular subject of the evening, " Modes of Raising Water," was 

 then taken up. 



The Chairman. — I proposed this subject from a selfish motive — the hope 

 of getting some information in relation to it. I shall open it with a few 

 very elementary remarks. Raising water is the same as raising any other 

 substance; the power required is in direct proportion to the weight raised, 

 and the height to which it is raised. The object of most of our devices is 

 to avoid expending power in the production of incidental effects, as the 

 overcoming of friction, etc. The first plan adopted was doubtless that of 

 dipping up the water in a bucket or other vessel, and perhaps this is more 

 economical of power than any other plan that has ever been devised. The 

 amount of friction is inappreciable. When wells were too deep to be 

 reached by the arm, it was necessary to let down the bucket with a rope, 

 and if a large bucket was used, it was found convenient to attach it to a 

 lever with a partially counterbalancing weight at the opposite end of the 

 lever, and thus the sweep came into use. Or the rope was passed over a 

 drum, with a smaller drum on the same shaft for the counterbalancing 

 weight. But when wells were dug in dusty cities, it was necessary to 

 cover them over, and pumps had to be used. These are simply plans for 

 lifting the water, the bucket being made small, and attached to a rod 

 instead of a rope. In this case there is a great increase of friction, 

 requiring a larger expenditure of power. I should like to hear from gen- 

 tlemen present an account of the more complicated plans that are now 

 •employed. 



Mr. Fisher. — I have a plan for taking water from a ship, which has not 

 been suggested by any one else that I am aware of. It is to run a pipe 

 from the hold of the vessel out of the stern, when the forward motion of the 

 vessel would cause the water to flow out through the pipe. I have made 

 some calculations, which show that a speed of twenty miles an hour would 

 discharge the water under at least four feet head, making a very large 

 allowance for friction, etc. 



Mr. Dibben. — The calculations may be all right, but I suspect there would 

 be practical difficulties in the way of arranging the pipes. Ship masters, 

 too, have very strong objections to making holes in the sides of their ships. 

 They are very much disinclined to adopt any alterations in their pumps. I 

 have seen ships within a short time with the pump on the hurricane deck, 

 so that all the water had to be raised twice as high as was necessary. 

 There is nothing that mariners are more afraid of than getting their pumps 



