Cost of air used £6 14 0½ £18 13 3
Oil. waste, packing, etc. 1 0 0 1 0 0
Interest, depreciation,
etc., 12½ per cent. on
£10, the cost of engine
per indicated
horse power 1 5 0 1 5 0
-------- ---------
£8 19 0½ £20 18 3

The maximum case would apply only to direct acting engines, such as
Tangye pumps, air power hammers, etc., where the air is full on till the
end of the stroke, and where there is no expansion. The minimum given is
at the average rate of 5d. per 1,000 cubic feet; but as there will be
rates below this, according to a sliding scale, we may fairly take it
that the lowest charge will fall considerably below £6 per indicated
horse power per annum.--_Journal of Gas Lighting_.

* * * * *




THE BERTHON COLLAPSIBLE CANOE.


An endeavor has often been made to construct a canoe that a person can
easily carry overland and put into the water without aid, and convert
into a sailboat. The system that we now call attention to is very well
contrived, very light, easily taken apart, and for some years past has