ON THE DEVELOPMENT OF LIGHT FROM COAL-GAS. 123 



material, which lie calls " albatrine," but with openings of 4^- inches 

 diameter. These globes are constructed of various sizes to suit certain 

 burners, both batwing and Argand, and the combinations are known by- 

 certain names, such as the Westminster, Viennese, Frankfort, Italienne, 

 Parisienne, &c. Some of these arrangements are fitted with Argands, 

 and some with batwings, and some have attached to them regulator's 

 with the intention of maintaining a constant pressure. 



One of the difficulties connected with gas illumination is that the 

 pressure in the mains varies considerably in different parts of a town, 

 and at different hours of the day and night. One result is that a system 

 of lighting adapted for a part of a town situated in a low level will show 

 inferior results in a more elevated situation. A rise of 10 feet gives, 

 roughly, a tenth of an inch of increase of pressure, so that it may easily 

 happen that in the same town or city the pressure in one place may be 

 1 inch, while in another it may be 2^ inches. Again, the pressure of the 

 gas as sent out from the gaswork is altered from time to time in accord- 

 ance with the consumption, and as public works, shops, &c, are suddenly 

 lit up or extinguished at certain hours, private consumers are annoyed in 

 the one case by a falling off in the amount of light, and in the other by 

 a flaring flame and hissing sound, both of which are very irritating. The 

 cure for these evils is to be found in the use of governors or regulators. 

 Every district of a town, the elevation of which is such as to affect appre- 

 ciably the pressure of the gas, should have a governor, which may either 

 be self-acting to maintain a constant pressure throughout the day, or to 

 vary sympathetically with the governor at the gasworks. Many of these 

 have been invented, among which may be mentioned those of Catheis,. 

 Peebles, and Eoulis. The pressure in the mains should not be reduced 

 below 12 or 14 tenths of an inch ; but as over that is too high a pres- 

 sure for the economical burning of gas, each house should have a regulator 

 in order to reduce the pressure constantly to about 7 or 8 tenths. Some 

 of these regulators are dependent on the action of the gas upon a broad 

 leather disc, attached to which is a ball-and-socket valve, while others 

 have metal or glass bells floating in mercury, and acting upon a valve of 

 the same kind. Both of these work satisfactorily. Among the best dry 

 regulators are those of Sugg of London, and Peebles of Edinburgh, 

 while probably the best mercurial governor is that of Busch of Oldham. 

 In the case of public works, and other buildings consisting of several floors, 

 a regulator should be placed in each floor, and one should be placed on 

 each street lamp, for which a special form is constructed. The best street 

 lamp regulators made in this country are those of Peebles and Sugg, 

 but a very admirable little instrument called a rheorneter is extensively 

 used in Paris, and has been tried with tolerably successful results in 

 several of our own cities. It is the invention of M. Gh-aud of Paris, and 

 it differs from the regulators which maintain a constant pressure in 

 delivering a constant volume of gas, with any size of burner, and under 

 any pressure, provided that the pressure is not less than 7 or 8 tenths of 

 an inch, and the burner is sufficiently large to pass the requisite quantity 

 of gas. The recently invented " needle governor " of Peebles is similar in 

 principle, and maintains a given volume of gas with remarkable constancy. 



