tructors of turbine steam-engines designed for electric
lighting. The object was to get an initial speed which would be so
great as to admit of the coupling of the dynamo to the revolving shaft
of the turbine steam-motor, without the employment of too much
reducing gear. In the case of the wind-motor the eighteenth century
miller was compelled to make the arms of his mill of gigantic length,
so that, while the centre of the wind pressure on each arm was
travelling at somewhere near to the rate of the wind, the axis would
not be running too fast and the mill stones would never be grinding so
rapidly as to "set the _tems_--or the lighter parts of the corn--on
fire."

The dynamo for the generation of the electric current demands exactly
the opposite class of conditions. We may therefore surmise that the
windmill of the future, as constructed for the purposes of storing
power, will have a long barrel upon which will be set numerous very
short blades or sails. Reducing this again to its most convenient
form, it is plain that a spiral of sheet-metal wound round the barrel
will offer the most convenient type of structure for stability and
cheapness combined. At the end of this long barrel will be fixed the
dynamo, the armature of which is virtually a part of the barrel
itself, while the magnets are placed in convenient positions on the
supporting uprights. From the generating dynamo the current is
conveyed directly to the storage batteries, and these alone work the
electric motor, which, if desired, keeps continually in motion,
pumping, grinding, or driving any suitable class of machinery.

It is rather surprising to find how relatively small is the advantage
possessed by the vane-windmill over the fixed type in the matter of
continuity of working. During about two years the Author conducted a
series of experiments with the object of determining this point, the
fixed windmill being applied to work which rendered it a matter of
indifference in which way the wheel ran. With the prevailing winds
from the west it ran in one direction, and with those of next degree
of frequency, namely from the east, it turned in the reverse
direction. The mill, however, was effective although the breeze might
veer several points from either of the locations mentioned. It was
found that there were rather less than one-fourth of the points of the
compass, the winds from which would bring the wheel to a standstill or
cause it to swing ineffectively