ADDRESS. 45 
miles of pipes of various sizes, through which gas was supplied equivalent 
in heating value to 8,650,000 tons of coal per annum. Since then the 
consumption in and around Pittsburgh has probably been at least 
tripled. At the close of 1886 six different companies were conveying 
natural gas by pipes to Pittsburgh from 107 wells; 500 miles of pipe, 
ranging in diameter from 50 inches to 3 inches, were used by these 
companies, 232 miles of which were laid within Pittsburgh itself. The 
Philadelphia Company, the most important of these associations, then 
owned the gas.supply from 54,000 acres of land situated on all the anti- 
clinals around Pittsburgh, but drew its supplies only from Tarentum 
and the Murraysville field. It supplied, in 1886, 470 factories and about 
5,000 dwellings within the city, besides many factories and dwellings in 
Alleghany and in numerous neighbouring villages. The average gas- 
pressure at the wells, when the escape is shut off, is about 500 lb. per 
square inch, and in the case of new wells this pressure is very greatly ex- 
ceeded. In order to minimise the danger from leakage, the gas-pressure 
in the city is reduced to a maximum of 13 lb., and is regulated by valves 
at a number of stations under the control of a central station. The usual 
pressure in the larger lines is from 6 to 8 lb., while in the low-pressure 
lines it does not exceed 4: to 5 ounces. 
The effect of the change from coal gas to natural gas upon the atmo- 
sphere over Pittsburgh has been most marked: formerly the sky was 
constantly obscured by a canopy of dense smoke; now the air is clear, 
and even white paint may with impunity be employed for the house 
fronts. 
The very rapid development of the employment of natural gas is not 
confined to the neighbourhood of Pittsburgh; it is used for heating 
purposes in the cities of Buffalo, Erie, Jamestown, Warren, Olean, Brad- 
ford, Oil City, Titusville, Meadville, Youngstown, and perhaps twenty 
more towns and villages in Pennsylvania and North-western New York. 
_ In North-western Ohio, the cities of Toledo and Sandusky, the towns of 
Findlay, Lima, Tiffin, Fostoria, and others in that section are also supplied 
with natural gas ; a pipe line has moreover been recently laid to Detroit, 
Mich., and it is estimated that in these localities 36,131,669,000 cubic 
_ feet of the gas were consumed during last year, superseding 1,802,500 tons 
of coal. To the south-west of Pittsburgh there are many smaller places 
which consume natural gas ; it also occurs in considerable quantity, and 
is being utilised, in Indiana (whence an account has recently reached us 
of a terrific subterranean explosion of the gas); and it is at the present: 
time contemplated to carry a natural gas-supply to Chicago. 
The utilisation of the natural gas of the Russian oil-fields, although 
of very ancient date, has hitherto not been extensive, neither does the 
magnitude of the supply appear to bear comparison with that of the 
Pennsylvanian district. 
_ A form of gaseous fyel which has long keen known to technical 
