Chap. XIX.

ATMOSPHERE AS A MOVING POWER.

1210

highest winds. The plan of thehead is extremely simple, and re-quires to be merely balanced.

The self-adjusting Cap is turnedround by the force of the wind,which acts upon a flyer or fan, socontrived that it always presentsthe sails in the proper direction,by means of a smaller pair at-tached to a gallery projecting fromthe back of the cap ; on the axle ofthis fan is a pinion engaging inanother wheel attached to the in-clined axis,atthe otherend of whichis fixed a bevelled pinion workinga wheel on the vertical spindleof another pinion, which is en-gaged in the cogs, arranged roundthe outside of the fixed curb, sothat when the flyers are turned, thehead of the mill is slowly turnedround, the power depending uponthe ratio of the several radii. Care

Fig. 1915.

SELF-ADJUSTING CAP.

must be taken that its action be sufficient to make a change when sudden gales arise, as

Fig. 1916.

SELF-ADJUSTING CAP.

it has frequently occurred, where these self-acting caps have been introduced, that if thebrake had not been made use of in time to turn the sails rapidly, the mill would have fired.

The sails of wind-mills are of variouskinds, and the fixingthem requires greatskill on the part ofthe millwright. Whenthe shafts are of cast-iron, they have attheir extremities twosockets to receive thearms, also of the samemetal ; these, afterbeing inserted, arefurther secured bytwo pieces of timber,

Fig. 1917.

PLAN OF SELF-ADJUSTING CAP