-FLYING-MACHINE WORK. 173 
Methylated spirits of wine, “commercially pure, was decided to 
be the cleanest and most reliable fuel obtainable, and its receptacles 
were placed on the top of, inside and underneath the coil, the 
vapourized spirit mixed with various quantities of air spurting into 
the furnace: the whole being encased in asbestos card. As much 
as 6°9 cubic inches of water has been evaporated by 1-7 cubic 
inches of spirit in eighty seconds making one hundred and eighty- 
two double vibrations of the wings which have the same dimens- 
ions as those of Nos. 14 and 16. The spirit holder and burner 
have undergone many changes, and in larger engines the spirit will 
have to be pumped by the engine instead of the whole amount of 
fuel being put on at once. 
No. 17 Engine (steam) Plates x., x1., is of the usual vibrating 
type with the addition of the feed pump, 5:2 m. in diameter, which 
is single acting.* A cock is provided for reducing the quantity of 
water pumped, but it has not been used; if all the water is not 
evaporated it cannot endanger the cylinder covers as the valve 
does not cut off appreciably for compression and expansion. All 
the springs and catches about the valve are abolished. The valve 
cylinder ends are reduced in area to the size of the steam passages 
by caps, so that the reaction of the exhaust steam forces the valve 
to the end of its cylinder directly the port opens. Possibly the 
caps are unnecessary, if so, they serve to limit the travel of the 
valve. The valve cylinder has four port holes at each end with 
an annular space outside. There is a difficulty in grinding in the 
valve if there is only one port for each passage. The main piston 
and cylinder are made of brass and there are no packing rings. 
The relation between the cylinder capacity and boiler is :— 
Cylinder se a Ste 2-2 cubic inches. 
Steam and water space of boiler ... 2°8 + 
External surface of boiler ... ... 113 square inches. 
Internal surface of boiler... oe) hTD 
39 
Sundry chronograms have been taken showing that 1:66 double 
vibrations per second are made with fifty-five pounds steam 
* Plate x. has the feed pump ram marked 4:2 m. instea osm. 
