SCIENTIFIC NEWVS. 



[April 6, 1888. 



THE HUNSLET MECHANICS' INSTITUTE. 

 In a lecture on "Water," Professor Smithells, of the 

 Yorkshire College, dwelt upon the 'difference between 

 pure and impure water. A sample of what people 

 called pure water was, he said, far from being pure. 

 The difference between pure and impure water was 

 evident to the eye alone when seen in large quantities. 

 If they converted a quantity of Leeds water into steam 

 they would find that a certain amount ot solid substance 

 adhered to the sides of the vessel in which it was 

 boiled. On boiling ordinary water by far the largest 

 proportion of its substance disappeared in steam ; but 

 there was left a residue of solid matter, which existed in 

 different waters in a greater or lesser degree, but in rain 

 water lecst of all. Pure water could be entirely 

 converted into rteam, and left no solid matter. Distilled 

 water was most unpalatable, owing to the absence of 

 solids and gases. In passing through the air, in its 

 descent, rain gathered and dissolved some of the air, 

 which was found to exist in the proportion of eighteen 

 gallons of air to a thousand of water. It water did not 

 contain those eighteen gallons of air, marine life would 

 not be possible. On reaching the earth, and coursing 

 over it in streams, the water came into contact with the 

 solid constituents of the earth's crust. For the most 

 part the substances of which the latter was composed 

 were not soluble in water, but there were certain 

 substances which were dissolved. Tine most important 

 solid substances in natural water were known as common 

 salt, chalk, gypsum, magnesium, and ammonia and its 

 compounds. It was self-evident how salt and gypsum, 

 and such substances, got into water ; but chalk was not 

 soluble in water unless the latter contained a certain 

 amount of carbonic acid gas. This gas was to be found 

 in all natural water, but in some a great deal more than 

 others. Lime was a desirable constituent of water. 

 Water containing lime was not only a drink but a food, 

 on account of its bone-forming capacity. 



NEWCASTLE FOREMEN ENGINEERS' AND 

 DRAUGHTMEN'S ASSOCIATION. 

 At the meeting of the 17th March, Mr. A. Taylor read a 

 paper on " Latent Heat of Steam and Steam-engine 

 Efficiency." The author divided his subject into two 

 heads — first, latent heat of steam ; and second, steam- 

 engine efficiency. He described the foundation on which 

 the first part of the subject rested as follows : — ist. 

 Water has least bulk, that is greatest density, at a 

 temperature of 39 degrees, and its bulk or volume 

 increases as its temperature is raised above 39 degrees. 

 Sea-water in rising from 39 degrees to 212 degrees 

 expands 5 per cent, of its original volume ; 2nd, it is 

 acknowledged that if the particles of a pound of water at 

 its greatest density (namely, 39 degrees) are agitated in 

 such a manner as to absorb 773 ft. lbs. of mechanical 

 energy, the temperature of the pound of water will be 

 increased one degree ; 3rd, the amount of heat necessary 

 to raise water of greatest density one degree in temperature 

 is called its specific heat at that temperature ; this 

 amount of heat is also called a unit of heat, and is in 

 mechanical energy equivalent to the before-mentioned 

 772 ft. lbs. Steam-engine efficiency was the second 

 branch of his subject, which he subdivided : — ist. By the 

 capability of the boiler, including the furnace to convert 

 and transfer to the water in the boiler a percentage of the 



total heat which can be theoretically generated by the 

 perfect combustion of a given amount of coal, or, in other 

 words, the evaporative efficiency of the boiler ; and 

 the capability of the cylinder or cylinders of the engine 

 to convert a percentage of the heat of the steam into work 

 done on the piston ; in other words, to convert the energy 

 in the steam into horse-power. In conclusion, he said 

 that coal containing mechanical energy equal to 100 horse- 

 power, gives 7 1 horse-power to the boiler, and the boiler 

 gives this 71 horse-power to the engines, and the steam 

 gives 12 horse-power to the piston, but this is not allow- 

 ing for condensation which must take place in the 

 cylinders on account of cold surface, etc. If this con- 

 densation and other losses be allowed Tor, the 12 horse- 

 power may safelj' be reduced to 10 horse-power. When 

 from this is taken the loss in friction of the moving parts 

 of an ordinary marine engine, and the loss of propeller 

 efficiency, the actual efficiency of the whole machine can- 

 not exceed 5 per cent,, in other words from coal contain- 

 ing mechanical energy equal to 100 horse-power we only 

 get about 5 per cent, horse-power to drive a modern 

 steamer. 



JUNIOR ENGINEERING SOCIETY. 

 At the last meeting of this Society three brief papers on 

 " A New Pneumatic Hand-tool," " Hooke's Joint," and 

 " A Question in Steam Engine Efficiencj'," by Mr. 

 F. H. Lewis, Mr. A. H. Tyler, and Mr. S. H. Wells 

 respectively, were read and discussed. Mr. Lewis 

 described the tool, a specimen of which was exhibited, 

 as consisting of a cylinder, one end of which was closed 

 by a spindle tool-stock held in position by a strong 

 spring, and in which an air-pressure of 25 lbs. to 40 lbs. 

 per square inch caused a piston to very rapidly recipro- 

 cate and to deliver a corresponding succession of blows 

 to the head of the tool stock, in which tools of various 

 forms, according to the character of the work, could be 

 fixed. The applications of the tool were numerous — 

 wood, stone, and iron being worked with equal facility. 

 Mr. Tyler exhibited three models in illustration of the 

 principle and development of Hooke's joint, and entered 

 into a detailed explanation of the salient features of 

 their construction. The question raised by Mr. Wells 

 was as to whether, in considering the efficiency of a 

 steam engine, the power required for driving the 

 auxiliary engines should be regarded wholly as a loss. 

 The conclusions drawn by the author were that in refer- 

 ence to the air, circulating, and bilge pumps, the power 

 necessary to work them was lost, but as regards the feed 

 pump nearly all the energy expended in driving it was 

 recovered, and that it was therefore incorrect when 

 ascertaining the total h.p. developed from the coal 

 burned to add the h.p. indicated in the cylinder of the 

 feed pump to that of the main and auxiliary engines, 

 which appeared to be the course usually adopted, judging 

 from reports of trial trips which had come under the 

 author's notice. 



EDINBURGH GEOLOGICAL SOCIETY. 

 Mr. Hugh Miller, at the meeting on the i6th March, 

 communicated a paper by Professor E. W. Claypole on 

 " The Eccentricity Theory of Glacial Cold versus the 

 Facts." Professor Claypole explained at the outset the 

 theory of Dr. James Croll, of Edinburgh, which accounted 

 for the glacial era by the increased eccentricity of the 

 earth's orbit producing a glacial climate on the hemi- 



