JUNE 13, 1884.] 
was at one time, about twenty-five to fifty years ago, 
the principal source of supply for the larger markets 
of the country, and especially for New-York City; 
and the trade between these two places was of great 
importance. The Cape-Cod grounds are now, how- 
ever, so nearly depleted that the annual catch is of 
very slight value. Other important areas have shown 
indications of a similar decrease; and the market 
supplies have been increased from year to year only 
through a great extension seaward of the fishing- 
grounds, and the much greater number of traps used. 
A suggestive indication of the decrease in abundance 
of lobsters is furnished by the marked decrease in the 
average size of those now taken to supply the trade. 
The fact was noted that the lobster is not a truly 
migratory species, but simply moves into slightly 
deeper water on the approach of cold weather, to re- 
turn again to the same shallow areas as the spring 
advances. Continued over-fishing in any one region 
will therefore tend to reduce the stock of lobsters 
in that region, without the probability of its being 
rapidly replenished by migrations from a neighboring 
region; and the greater or less depletion of many 
areas may be explained in that way. 
The solution of the problem as to how the fishery 
may be protected in the interests of the fishermen 
and the trade must be reserved for future investiga- 
tions; but existing laws do not appear to give the 
desired benefits. 
On Tuesday evening the association met in the hall 
of the National museum, to listen to an address by 
Hon. Theodore Lyman of Massachusetts, who re- 
viewed the work of the U.S. fish-commission and of 
the state commissions in an able manner. 
Hon. Theodore Lyman was elected president of the 
society for the ensuing year; and during the return 
trip from the river-excursion on the steamer Fish- 
hawk, the name of the association was, after consid- 
erable discussion by the members present, changed 
to the ‘ American fisheries society.’ A conference 
of all of the state fish-commissioners present at the 
meeting, with the U.S. commissioner of fish and 
fisheries, Professor Baird, was held on the 15th. 
MEETING OF MECHANICAL ENGINEERS 
AP PiPppseponRGH. 
THE meeting of the American society of mechan- 
ical engineers at Pittsburgh, May 20-24, was in many 
respects one of the most interesting that has been held. 
The attendance was as good as usual, say twenty-five 
per cent of the membership, and the quality of the 
papers above the average. The arrangements for the 
social comfort and enjoyment of the guests were not, 
however, so complete as at the last spring meeting. 
It was a mistake, that the announcement of a conversa- 
zione and social re-union was not carried out, and an 
opportunity given, early in the meeting, for the forma- 
tion and renewal of acquaintances. The excursions 
so generously provided were of great interest; but we 
venture the assertion that the mass of the visitors 
gained but little accurate information. By providing 
SCIENCE 
723 
for such an occasion an appropriate manual or guide, 
or possibly a larger reception committee, the advan- 
tage to the guests can easily be quadrupled. It might 
even be better, as was done at the last meeting, to 
devote the whole day to a well-planned visit to a sin- 
gle establishment. 
The society met in joint session with the Engineers’ 
society of western Pennsylvania, whose president, Mr. 
Miller, welcomed the visitors, and invited their presi- 
dent, Prof. John E. Sweet (formerly of Cornell uni- 
versity), to the chair. The evening of May 20 was 
devoted to the report of Messrs. Roberts, Phillips, 
Hunt, McDowell, and Jarboe, — a committee appoint- 
ed, at the January meeting of the local society, to in- 
vestigate the whole subject of natural gas. There are 
also a city, and an underwriters’ committee on the 
same subject. 
Though Pittsburgh is within reach of three or four 
prolific localities, and gas has been used for many 
years, it is but recently that any organized effort has 
been made to use it on a large scale. Already there 
are a hundred and fifty companies chartered in the 
state, representing over two million dollars; and gas is 
brought from eight to twenty-five miles for use in the 
city. Five-inch mains are being followed by eight-inch, 
new wells are being bored, and the time when Pitts- 
burgh shall become a smokeless city may not be far 
distant. Though the gas is used under a pressure of 
a few ounces, the pressures at the wells run from fifty 
to a hundred and twenty-five pounds: this is due to 
the friction in the mains, five pounds being allowed 
for each mile. If the flow be shut off the pressure 
runs up much higher, and great difficulty has been 
experienced in making tight joints; cast-iron is too po- 
rous, and ordinary pipe-threads do not fit well enough. 
A number of new coupling-devices were exhibited, 
in some of which a lead packing was used. No al- 
lowance for expansion need be made, as the gas main- 
tains an even temperature of about 45° F. When 
gas is allowed to burn freely at the mouth of a well, 
the cold produced by the expansion is such that ice 
has been projected through the flames. 
The gas is used in all kinds of furnaces for making 
steam, iron, glass, etc.; and electric-light carbons, and 
the finest lampblack for printing-inks, are made from 
it: but it is-used with suicidal wastefulness, which 
causes anxiety, aS many wells give out in less than 
five years. The report looks to its economic and safe 
control. For household use it might otherwise be 
dangerous; and such use has commenced, though no 
practicable method of deodorizing it has been found. 
Being composed largely (ninety-six per cent) of marsh- 
gas, its value as a heating-agent is high, and its den- 
sity is about half that of air. One pound (23.5 cubic 
feet) of gas has a theoretical evaporating-power of 
twenty-four pounds of water, twenty pounds having 
been actually evaporated. The best method of burn- 
ing it is not generally known: experiments with in- 
jector-burners show that they do not suck in sufficient 
air for complete combustion, and the best results have 
been from numerous jets in contact with the whole 
heating-surface of the boiler. The value of the gas, 
as compared by evaporation tests with coal at $1.40 
