1850.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



29; 



turned was 36 feet in height, and 17 feet in diameter at the base, 

 the rock being so small as to preclude a greater diameter. The 

 author then concluded by stating the following desiderata, which 

 bethought important: — 



1st. Continued observations so as to ascertain constants for the 

 Atlantic and German Oceans and the Irish Sea. 



2nd. Relative forces of the same wave both above high-water 

 and below low-water levels. And 



3rd. Relative forces of the same wave against vertical and 

 sloping surfaces. 



AIK A.VD WATER IN TOWNS. 



On the Air and Water in Tounm, and the action of Porous Strata 

 on Water and Organic Matter. By Dr. R. A. Smith. 



It is a matter of great importance to find from what source it is 

 best to obtain water for large towns, and how it is to be collected. 

 To these points Dr. Smith particularly directs attention. Regard- 

 ing the conditions of many springs, whicli never become muddy, 

 but possess a constant brilliancy and a very equal temperature 

 at all seasons of the year, the author thinks that there is a p\irify- 

 ing and cooling action going on beneath. The surface water from 

 the same place, even if filtered, has not the same brilliancy; it 

 has not the same freedom from organic matter, neither is it equally 

 charged with carbonic acid oroxygengas, — there are other influences 

 therefore at work. The rain which falls has not the purity, al- 

 though it comes directly from the clouds; it may even be wanting 

 in cleanness, as is often the case. Springs rise tlirougli a great 

 extent of soil, and collect a considerable amount of inorganic 

 salts; and it is shown by Dr. Smith that their purity is due entirely 

 to the power of the soil to separate all organic matter, and at the 

 same time to compel the mixture of carbonic acid and oxygen. 

 The amount of organic matter removed in tliis way is surprising, 

 and it is a most important and valuable property of the soil. The 

 change even takes placo close to cesspools and sewers; at a very 

 short distance from the most offensive organic matter there may 

 be found water having little or none in it. As an agent for purify- 

 ing towns, this oxidation of organic matter is the most e.xtraordinary, 

 and we find the soil of towns which have been inhabited for 

 centuries still possessing this remarkable power. St. Paul's 

 Churchyard may be looked upon as one of the oldest parts of 

 London, and the water from the wells around it is remarkably 

 pure, and the drainage of the soil is such tliat there is very little 

 of any salts of nitric acid in it. If the soil, says Dr. Smitli, has 

 such a power to decompose by oxidation, we want to know how it 

 gets so much of its oxygen. We must, however, look to the air 

 as the only source, and see how it can come from it. When water 

 becomes deprived of oxygen, it very soon takes it up again, — as 

 may be proved by experiment. This shows us that as fast as the 

 oxygen is consumed by the organic matter it receives a fresh 

 portion, conveyed to it by the porous soil. Several experiments of 

 the following character were given, to show the filtering power of 

 the soil: — .V solution of peaty matter was made in ammonia; the 

 solution was very dark, so that some colour was perceived through 

 a film of only the twentieth of an inch in thickness. This was 

 filtered through sand, and came out perfectly clear and colourless. 

 Organic matter dissolved in oil of vitrol was separated from it by 

 a thickness of stratum of only i inches. A bottle of porter was 

 by the same process deprived of nearly all its colour. The material 

 of which this filter is made is of little importance. One of the 

 best, according to Dr. Smith, as far as clearing the vvater is con- 

 cerned, being of steel filings; oxide of iron, o.xido of manganese, 

 and powdered bricks, all answer equally well. This shows that 

 the separation of the organic matter is due to some peculiar 

 attraction of the surfaces of the porous mass presented to the 

 fluid. 



REGISTER HYGROMETER. 



This instrument was invented by Mr. Appold, for the purpose 

 of keeping the atmosphere of his house, in Finsbury-square, at 

 one regular degree of moisture. It is made so that a variation of 

 one-quarter of a degree in the hygrometric state of the atmosphere 

 will open a valve capable of supplying ten quarts of water per 

 hour, and convey it on to the surface of warm pipes covered with 

 blotting paper, by which the water is evaporated until the atmo- 

 sphere is sufficiently saturated, and the valve thereby closed. 



A lead pencil k, attached, registers the distance the hygrometer 



travels, and thus a sheet of paper moved by a clock would show 

 the hygrometric state of the atmosphere at any period of time. The 

 instrument is made with two bulbs, a and b, of a cylindrical shape, 

 1 inch diameter and 1^ inch long, placed vertically, so that the 

 surface of the mercury may always be the same size; the bulbs are 

 about 9 inches apart, with mercury enough in them to fill one. and 

 connected together by a glass tube, that the mercury may flow 

 freely from one to the other. A little ether is placed in each bulb, 

 and the remaining space filled with the vapour from the ether. 

 The bulbs are fixed upon a balance, so that when one bulb becomes 

 warmer than the other, the ether forms vapour in one, and con- 

 denses in the other, by which means the mercury is driven from 

 one bulb to the other. 



It will be observed that the wet bulb B, is placed under the 

 fulcrum, for the purpose of keeping it always in contact with the 

 water; the other end a, is held up by a spring e, connecting 

 the two horizontal levers d, and c, so that it can be adjusted to 

 agree exactly with the action of the mercury: this is done with 

 both bulbs dry, and made to stand in any position, the spring 

 counteracting the weight of the mercury. When in use, the 

 spring and levers are lowered, allowing as much mercury to flow 

 into the dry bulb as may be required; the drier the atmosphere is 

 required to be, the lower the dry bulb must be placed. The valve 

 F, is fixed to one end of the top lever d, that the lever g, which 

 opens the valve, may be always in the same situation relative to 

 the hygrometer. In the place to wliich it belongs the water is 

 laid on n ith a gutta-percha pipe. The brass vessel at top serves 

 for a temporary cistern, to show the action of the valve, h, weight 

 attached to the lower lever c; l, set screw for upper lever; m, 

 cistern that receives the water from the valve, the overflow of 

 which goes on to the pipes; n, overflow pipe. 



DOOR SPRING hinge. 



An improved Door Spring. Invented and patented by Georgk 

 Beattie, builder, Edinburgh. 



In all steel springs there is a defect in the want of uniformity of 

 pressure throughout the travel of the door, which usually increases 

 as the door is opened wider, and makes it disagreeable to the per- 

 son opening it; and when it closes, a rapid slam takes place; and 

 if the door has glass in it, it is liable to be broken. By the im- 

 proved hinge these defects are avoided, and there is no metal 

 spring of any kind used, the motive power being obtained by the 

 pressure of the atmosphere (which is well known to exert a pres- 

 sure of 15 lb. to the square inch) acting on one side of a piston ; 

 the other side being a vacuum. In applying this pressure to shut 

 a door, about 2 lb. to the square incli is lost by the friction of the 

 machinery. The pressure of the air acts simply as a counter- 

 balance on the piston, the resistance being uniform throughout the 

 travel of the dooi when opening it, and when shutting the door 



