Mr. MacKain on the Compressum of Water. 265 



I cannot avoid calling tho attention of the Society to a slight 

 though rude corroboration of the theory now advanced — the belief of 

 seamen in the greater density of water at great depths, than is gener- 

 ally admitted. They find a great difiiculty in sounding in deep 

 water, but with very heavy leads. From the increased weight of the 

 leads required, and from the diminished effect on the hand when 

 sounding, seamen are almost universally impressed with the idea that 

 the loss of effect is produced by the increased density of the water. 



An additional interest may be attached to the further investigation 

 of this subject from the possible effect it may have on geological 

 speculations. At the great depths of the ocean, and amid the pro- 

 found stillness which reigns in these parts where the tides do not 

 act, many substances of great specific gravity may float in the mass of 

 waters, and thus be permitted to obey the slight but constant im- 

 pulses of elective attraction — producing crystals, and leading to the for- 

 mation of crystallized rocks. But I shall not enter into any specula- 

 tions on this subject 



I shall only add, that if water be compressible to the degree I have 

 now advanced, and the substances now stated were incompressible, 

 bricks will float at a depth of 28,330 feet; granite at 56,600 feet, or 

 10 miles ; and cast-iron at 200,000 feet, or 39 miles. 



Professor Gordon read a paper illustrating tho application of the 

 method of least squares to the reduction of " Provis's* experiments 

 on the flow of ivater through small pipes, and to a mathematical 

 formula, of simple application, for calculating the diameter of pipes, 

 the head, quantity of water, and length of pipe being given. After 

 the reading of the paper, Mr. John Wilson stated, that he had 

 been required to place a pipe of eight feet in length horizontally, so 

 that under a constant head or pressure of ten feet of water it should 

 discharge neither more nor less than 100 imperial gallons of water 

 per minute, and not being able to derive any information from such 

 engineers as lie had consulted, he had been under the necessity of 

 arriving at the proper result by numerous experiments. He considered 

 that it would be a fair test of tlie formula proposed if Professor 

 Gordon would calculate the true diameter of the pipe, from the data 

 given. It was accordingly agreed that Professor Gordon and Mr. 

 Wilson should compare their theoretical and experimental results at 

 next meeting. 



24<A April, 1844,— TAc President in the Chair, 



The secretaries of the different sections reported that meeiiiigs had 

 been held for the election of sectional office-bearers for 1844-45; the 



• Trans. Inst, of Civ. Eng. Vol. II. 



