1843.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



371 



Underpinning Walls. 



Concrete has been employed with great success by G. L. Taylor, 

 Esq., Architect to the Admiralty, for underpinning walls of consi- 

 derable extent. At Chatham the walls of a storehouse 540 feet in 

 length were underpinned with concrete in about four months. The 

 walls of this building had been founded about 40 years before on 

 timber sleepers and planking, which had since decayed. It was neces- 

 sary to excavate on each side of the walls to a depth of from 1(5 to 

 26 feet to take out the decayed timbers, which varied from 2 to 6 feet 

 in height, and were or 7 feet wide. The concrete was put in in a 

 liquid mass to within a foot of the bottom of the old walls; at this 

 level a large slate was bedded on the concrete, and the remaining foot 

 was presstd in by an iron frame with two strong screws on each side 

 of the wall. The concrete was placed in lengths of four feet, and the 

 next day the weight of the superincumbent wall, 50 feet high and 

 5 feet thick, was allowed to come upon it, and no subsidence has ever 

 been observed. In another building at Chatham which had settled 

 about three inches, Mr. Taylor raised the part affected to its proper 

 level, by forcing concrete under it in a similar manner. 



Ranger's Concrete Stone. 



Notwithstanding the failure of Ranger's patent cement stone when 

 injudiciously used, it is said to have been successfully employed on 

 several occasions. The Architect to the Admiralty, G. L. Taylor, 

 Esq., lias used it for building a school at Lee, on the model of the 

 Propylfea at Athens. 



In the concrete dock which was built at Chatham, Ranger's stone 

 was used in the form of blocks for the bottom, but the sides were 

 formed of concrete laid in mass and lined with granite. The expense 

 of this dock is said'to have been barely one-tenth of the amount which 

 a dock built wholly of masonry would have cost. 



The patent stone has also been partially employed at Woolwich in 

 a river wall at the east end of the dockyard. This wall is 270 feet 

 in length, 26 feet high, 7 feet broad at bottom, and four feet at top. 

 The work was at first commenced on the plan of the concrete wall at 

 Brighton, namely, by filling the concrete in mass behind a fence of 

 boards placed in front of the face. Latterly, however, the face of the 

 wall was formed of concrete blocks cast in boxes, with the massive 

 concrete filled in behind as a backing. 



Use of Beton by the French. 



When beton was first introduced into France, it was made up in 

 heaps and allowed to set. The heaps were then broken up, and the 

 br"ken lumps of beton or concrete thrown into the foundation which 

 they were intended to form. The following translation from Belidor 

 explains the method in which the beton was prepared for the works 

 of the Dock at Toulon. 



"Having fixed upon a spot where the ground is firm and solid, 

 take 12 parts of puzzolana and 6 parts of sharp sand free from earthy 

 particles; having mixed these together, form them into a circular 

 border about b' feet in diameter. Then fill the interior with 9 parts of 

 well burnt pounded quick lime, which is then to be quenched by ad- 

 ding water in small quantities. For maritime works sea water is to 

 be used, and the lime is to be turned over from time to time to facili- 

 tate the process of quenching. When the lime has been thus reduced 

 lo a paste, the border of sand and puzzolana is to be incorporated 

 with it. The whole being well mixed, throw into it 13 parts of broken 

 stone or stone drippings and 3 parts of broken iron cinder or scoria. 

 When this hitter cannot be obtained, 1G parts of broken stone may be 

 employed, or Hi parts of pebbles may be used, provided they do not 

 exceed the size of a lien's egg. The whole composition must then be 

 turned over and mixed together with shovels for about an hour, until 

 every part is thoroughly incorporated, and then the mass is to be 

 made up into small heaps. These heaps must remain untouched till 

 they acquire sufficient consistency to render a pickaxe necessary to 

 hreak them up. The time occupied in acquiring this consistency will 

 be 24 hours in the summer in warm countries, and in winter time 

 about three or four days. The heaps should be covered to protect 

 them from rain." 



Speaking of beton formed in this way, a writer in the French En- 

 cyclopiedie MHhodique, states that by way of experiment, a box con- 

 taining 27 feet cube was filled with it and plunged into the sea, where 

 it rem. lined for two months. When taken up the cohesion of the 

 heap was so great, that it was more difficult to break up than a block 

 of the best stone. 



ON WARMING AND VENTILATION. 



The objecls proposed to be accomplished by the different methods 

 of warming apartments, namely, those of producing an economical 

 heat, and at the same time of ventilating them, by causing a continual 

 circulation of air, in that state which is most conducive, to health and 

 comfort, are certainly of great importance and difficulty. 



In all the different modes by which these effects are usually more or 

 less produced, there are involved two very distinct principles, which 

 produce corresponding changes in the condition of the air contained 

 in the rooms where they are brought into operation. One of these 

 principles may be termed that of diffusing heat by radiation from fires 

 and heated surfaces, and the other that of heating air and making the 

 diffusion of it a vehicle for conveying heat to the places where it may 

 be required. The alterations produced in air by heat, so as to render 

 it more or less salubrious, according as one or other of these prin- 

 ciples is brought into operation in the different modes adopted to 

 warm and ventilate rooms, will now form the subject of consider- 

 ation. 



When rooms are warmed by radiated heat as from ordinary fires, 

 the temperature of the air which they contain is not so greatly raised 

 as when heated air is made the vehicle to convey and diffuse heat. 

 Bv radiation heat is diffused independently of air. Air, like all other 

 gases, is eminently a bad conductor of heat ; and hence it is that any 

 particle of air, being heated by contact with hot bodies, does not 

 appear to communicate any portion of the heat so acquired to the 

 contiguous particles, but its repulsive energies becoming developed, 

 it pushes the adjoining particles to a greater distance, and thus in- 

 creasing their volume and rendering their specific gravity less, they 

 necessarily rise and make room for others to follow the same course. 

 Nor is the mass of air in a room warmed by radiated heat being 

 transmitted through it, but this heat meeting with more solid forms of 

 matter, as with walls, &c., is absorbed by them. These walls and 

 other bodies thus becoming heated, radiate in all directions, heating 

 the air in contact with them; and this heated air then translates itself 

 as when heated in contact with fire. There is thus a continual but 

 gradual warming and circulation of air from all heated surfaces. 



Now if we suppose a room of the following dimensions, 30x20X20 

 feet, its cubic contents will be 12,000 feet. Let us suppose 1 foot, to 

 be the sectional area of the flue by which the products of combustion 

 and draft escape to the atmosphere, say with a velocity of 10 feet per 

 second. There would then be transmitted through such a flue in 10 

 hours, 360,000 cubic feet of air, which would renew the air of the room 

 30 times in that period, or 3 times in each hour during the day, an ex- 

 tent of ventilation sufficient for the most crowded apartment. 



It follows, from the non-conducting and non-absorbing power of air 

 in relation to heat, and from its being so frequently renewed, that the 

 temperature of air contained in rooms heated by ordinary fires can 

 never be great, but that the warmth which is felt in them is in a 

 great degree the effect of radiation, and not that of heated air. This 

 process of warming and ventilation is exactly that adopted in the 

 general habitation of man and all organized beings — a strong a priori 

 proof that their physical organization is adapted to such conditions of 

 the air as this process induces, and to no other. That such conditions 

 do obtain in the physical atmosphere, is evident. If air absorbed the 

 heat of the sun it could not reach the earth, but would produce a 

 temperature in the upper part of the atmosphere, that might precipi- 

 tate showers of rain little short of boiling heat, and cause tempests of 

 the most violent character, owing to the great extremes of tempe- 

 rature to which it would be liable, for under such circumstances the 

 temperature of all bodies must be as the quantity of heat they in- 

 tercept. 



In all methods of warming rooms by heated air, as by passing it 

 through hot pipes, or by means of cylinders containing coils of pipe, 

 heated by the circulation of hot water, the mode of diffusing heat is 

 the same. The air is made hot and poured into the. rooms in a con- 

 tinued stream, supplying heat and ventilation. The important dif- 

 ference between this' and radiation is, that the air is first made hot 

 and gradually communicates its heat to some parts of the room. 

 Air so circumstanced, must be hotter than any object to which it im- 

 parts heat, while the reverse is the case where radiation is employed. 

 As heated air is lighter than cold, it is quite evident it will chiefly 

 occupy the upper part of rooms so heated, especially when it is dif- 

 fused from one aperture, and that at some distance from the floor. 

 By testing with a thermometer, it is found that rooms heated by hot 

 air are increased in temperature about two degrees per foot from the 

 floor upwards, so that a person of ordinary dimensions might be said 

 to have his head in a summer and his feet in an autumn tempera- 



