1..J 



UNDULATORY FORCES. LIGUT. 



[MANAUKMENT or HAS. 



the middle or hollow of the flame ; and as these metals 

 expand unequally for the name tvmpvratiuv. tin- motion 

 of the longer r,-l is communicated to a small lever BO as 

 to movu a plug which opens or shuts the aperture that 

 delivers the gas. The temperature of the name is thus 

 made available as a means of regulating tlio supply of 

 gas, and so of keeping the flame at one uniform height 

 After the burner lias been once set, so as to produce the 

 necessary amount of light, any increase in the supply of 

 gas will immediately increase the size of the flame, and 

 this will cause the bar to expand and act on the plug so 

 as to shut off a portion of the gas. On the contrary, if 

 ipply is not sufficient, the bar contracts, and then 

 the aperture is opened. 



ON THE GENERU, MAN UiKMKXT OF GAS, 

 VKNTILATION, ETC. 



Gtncral Management of Gas. On the continent, the 

 government or municipal authorities enforce certain 

 regulations for the management and distribution of gas. 

 In Hamburg, for instance, the gas-fitters are obligi 1 i 

 perform their work in a certain manner : they must use 

 tubes of wrought iron, brass, or copper; and in cases 

 where these are not very easily adapted, tubes of drawn- 

 tin may be employed. The joinings must be made in a 

 durable and solid manner, either by means of sockets 

 ground in and cemented with iron cement, or by screw- 

 ing up, or by soldering. Any other mode of connection 

 is forbidden. The tubes must be placed in localities 

 where they are accessible, so that in case of leakage the 

 mischief may be easily remedied. The cocks must be 

 arranged in such a manner that they only make the 

 fourth part of a turn, and they must be fixed so as not 

 to be removable from the barrel. The gas-meters are to 

 be furnished by the gas company, and examined and 

 stumped by the adjusting commissioner. All the tubes 

 of one inch or more in diameter must have a stopcock, 

 so that they may be shut off from the main-pipe, in case 

 of fire. No one is allowed to make use of his gas- fittings 

 until the gas-fitter has tested their soundness, by means 

 of a pressure of one inch of mercury or fourteen inches 

 of water. All the gas-fitters are sworn to adhere to 

 these instructions ; and in case of any damage resulting 

 from negligence on the part of the fitter, private persons 

 are entitled to enforce their claims against him before 

 a civil court of justice. 



In a supplemental notice attached to the contract 

 made between the English Gas Company in Paris and 

 its consumers, the following regulations are recom- 

 mended : "To prevent any inconvenience in the use of 

 gas, it is requisite that the burners should not allow any 

 gas to escape in an unconsumed or imperfectly-consumed 

 state. This result is obtained by maintaining the flame at 

 a moderate height three inches and a quarter at most, 

 and confining it within a gloss chimney of eight inches 

 in height The rooms lighted should be carefully venti- 

 lated, even during the cessation of lighting, by openings 

 in the ceiling, through which the gas and its burnt pro- 

 ducts may escape. The plugs of the cocks should be 

 greased from time to. time, so as to prevent oxydatiou, 

 to facilitate their working. 



"In liijhtiny the gas, it is essential to open, in the 

 first instance, the main-cock, and then to apply the light 

 successively to each burner at the moment of opening its 

 cock, so as to prevent the escape of any unconsumed gas. 



"In fftinijuisliiitii Hie light, it is better first to close 

 the main-cock, and then to shut off the taps at each of 

 the burners. Whenever a smell of gas indicates that 

 there is a leak in the pipes, the doors and windows 

 should be opened, so as to cause a current of air through 

 the room ; and tin; main-tap should be closed. The con- 

 sumer should abstain from searching for any leak with a 

 light, but he should rather give notice to the company 

 and the gas-fitter. In case, whether by imprudence or 

 by accident, the escape shall have been ignited, the best 

 means of extinguishing it is to cover the aperture with a 

 wet cloth." 



These rules are of great importance, for very serious 



accidents have resulted from the explosion of gas mixed 

 with atmospheric air. A few years ago namely, in the 

 month of August, 1848 a fearful (lis-jster of this de- 

 scription occurred in Albany-street The gas accumulated 

 in the shop for a very short time only in fact, it had 

 been escaping no longer than one hour ami twenty 

 minutes from a crack in the meter ; the area of the room 

 was alx'iit 1 .li'-M cubic feet ; tmt when the gaseous mixture 

 ignited, it blew out the entire front of the premises, 

 carrying two persons through a window into a bark-yard, 

 and forcing another, by the violence of the shock, on to 

 the pavement on the opposite side of the street, where 

 she was picked up dead. For more than a quarter of a 

 mile, on each side of the house, the effects of the explosion 

 were severely felt, and the glass in most of the windows 

 of the neighbourhood was shattered. But the most 

 extraordinary evidence of its enormous power was ex- 

 hibited in the condition of the premises which imme- 

 diately faced the house that was destroyed : in one of 

 these the iron railings around the area were snapped 

 asunder, and in another a part of the roof and back 

 windows were carried to a distance of from 200 to 300 

 yards ; besides which, the pavement was torn up for a 

 considerable length. According to the official rej>orts 

 which were made to the insurance offices, it appears that 

 103 houses were injured by the explosion, and that the 

 damage done amounted to 20,000. 



Another accident, of a similar kind, occurred in the 

 mouth of July, 1850, at the llford toll-gate, whereby 

 three persons were severely injured. The space in which 

 the gas accumulated had an area of eighty cubic feet, 

 and the gas had been escaping into it at the rate of forty 

 cubic feet an hour for a period of fifteen minutes. A 

 piece of lighted paper was incautiously introduced for 

 the purpose of seeing where the leak was, and the 

 mixture immediately exploded, breaking up the flooring 

 of the room, blowing out the window, and knocking down 

 a large portion of the front and partition walls of the 

 building. These accidents were made the subject of 

 scientific investigation, and reports were furnished to the 

 journals by Dr. Arnott, Dr. Letheby, and Dr. Alfred 

 Taylor. In speaking of the latter, Dr. Letheby says 

 " It is difficult to form an estimate of the total explosive 

 force exerted by the gas on this occasion ; but I am led 

 to think that it was probably equal to about twenty 

 tons ; for when a column of mixed gas, consisting of one 

 part of coal gas and seven of air (the proportion in this 

 case), is fired, it expands to about five times its bulk, 

 and exerts a pressure of about four pounds on the square 

 inch." In the report given by Dr. Arnott on the ex- 

 plosion in Albany-street, it is stated, that the strongest 

 explosive mixture consists of one part gas and ten atmo- 

 spheric air, the expansion being in that case tenfold ; 

 and in a report furnished by M. Tourdes on the explosion 

 which took place at Strosburg in 18-18, it is stated, that 

 the greatest force results from a mixture of one part of 

 gas and eleven of air. These discrepancies doubtless 

 arise from the variations in the composition of coal gas ; 

 but it may be stated, in a general way, that from seven 

 to eleven parts of air to one of gas constitute the most 

 dangerous proportions; for if the gas or the air be much 

 in excess over these, the force of the explosion will be very 

 much diminished. This is exemplified in a very striking 

 manner by the admirable researches of Sir Humphry 

 Davy into the explosive properties of light carburet ted 

 hydrogen, or fire-damp; for they show, that while wsveii 

 or eight parts of air to one of gas produce the greatest 

 explosive effect, other proportions are less dangerous : in 

 fact, a mixture of equal parts of gas and air will burn, 

 but it will not explode. The same is the case with a 

 mixture of two of air, or even three of air, and one of 

 gas ; whereas four of air and one of gas begin to show an 

 explosive tendency ; and this becomes more and more 

 marked up to seven or eight of air to one of gas. His 

 experiments also prove, that one part of gas to ten, 

 eleven, twelve, thirteen, or fourteen of air were also 

 inflamed, but the violence of the combustion became less 

 and less ; and when the mixture consisted of fifteen parts 

 of air to one of gas, there was no explosion at all 



