be ascertained by the process of commencing a
trial with a known fire, and closing that trial at the end of six
hours, with the fire as nearly as possible in the same condition, the
consumption was 1.66 lb. of coal per gross indicated horse-power per
hour. So that, without taking into account the coal consumed in
raising steam from cold water, the engine worked for 1-2/3 lb. of coal
per horse per hour. I think it well to give these details, because
undoubtedly it is an extremely economical result.

ETHER ENGINE.

Our president alluded to the employment of ether as a means of
utilizing the heat which escaped into the condenser, and gave some
account of what was done by Mons. Du Tremblay in this direction. It so
happened that I had occasion to investigate the matter at the time of
Du Tremblay's experiments; very little was effected here in England,
one difficulty being the excise interference with the manufacture of
ether. Chloroform was used here, and it was also suggested to employ
bisulphide of carbon. In France, however, a great deal was done. Four
large vessels were fitted with the ether engines, and I went over to
Marseilles to see them at work. I took diagrams from these engines,
and there is no doubt that, by this system, the exhaust steam from the
steam cylinder, which was condensed by the application of ether to the
surface of the steam condenser (producing a respectable vacuum of
about 22 inches), gave an ether pressure of 15 lb. on the square inch
above atmosphere, and very economical results as regards fuel were
obtained. The scheme was, however, abandoned from practical
difficulties. It need hardly be said that ether vapor is very
difficult to deal with, and although ether is light, the vapor is
extremely heavy, and if there is any leakage, it goes down into the
bilges by gravitation, and being mixed with air, unless due care is
taken to prevent access to the flues, there would be a constant risk
of a violent explosion. In fact, it was necessary to treat the engine
room in the way in which a fiery colliery would be treated. The
lighting, for instance, was by lamps external to the engine room, and
shining through thick plate-glass. The hand lamps were Davy's. The
ether engine was a bold experiment in applied science, and one that
entitles Du Tremblay's name to be preserved, and to be mentioned as it
was by our president.

THE QUICKSILVER ENGINE.

These was another kind of marine engine that I think