Fig. 5. Darsham, Suffolk.
Below the first floor on this vertical shaft is another mortice spur wheel also called a wallower from which is driven a pair of vertical mill spindles by mortice pinions. The names of these being quants and stone nuts.
In the larger mills there are two stones in the head and one in the tail; at Newton and Tuxford there are only two, head and tail; while at Costock there are only two head.
The other fittings comprise a sack hoist, govenors, shoots, bins, weighing machines etc., etc., and all this is crammed into a space 12 feet wide by 18 feet long; and in many cases much smaller.
It is hard to imagine how at one time they found room to include an oat crusher and a flour bolter as well.
One of the most ingenious parts of these mills is the tail gear which is so common in Norfolk and Suffolk, but never seen in the Midlands and Lincolnshire.
Windmills had to be kept head to the wind, that is the plane of the sails must be kept at right angles to the wind.
Originally this had to be done by hand, by means of the tail pole, and it required constant vigilance on the part of the miller or his assistant until the famous Scotch millwright, Andrew Meikle, the inventor of the threshing machine produced the automatic tail jack, or fly. Fig. 5. Darsham, Suffolk.
It consists of a vane or fan of six or sometimes eight blades, set edgewise to the wind and geared to wheels running on the ground. These wheels and framing for the fly are securely fixed to the mill house by the tail ladder and struts.
Naturally, when the wind changes the fly revolves and drives the wheels turning the mill body round the post and always keeps the sails with the wind. The gear ratio is about 640 to 1,—i.e. it takes 640 revolutions of the fly to turn the mill round once.
Fig. 6. Broken crown tree, Costock, Notts.
The design and workmanship of this class of mill is generally of the very best; but in Nottingham the crown trees seem to have been too weak, and in one case at Costock, has broken, and allowed the mill to drop on the round house. Fig. 6. Conversely in Norfolk the windshafts have broken at the neck, and have in most instances been replaced by cast iron ones.
At Sprowston, Norwich, is I believe the earliest ball bearing extant. It forms the steady journal in the waist and encircles the post. It is 34 inches outside diameter and has 42 2¼ cast iron balls. There is no trace of machining anywhere on the bearing or the balls and the accuracy and cleanliness of the castings is remarkable.
Fig. 7. Occold, Suffolk.
The next type of mill is the smock, or frock which is built of a timber frame covered with weather board. It is so called from a supposed resemblance to a countryman's smock. Fig. 7. At Occold, Suffolk.
The last development is the brick tower, and as the internal arrangements of these are the same I will describe them together.
The cap revolves on the top of the tower on rollers, and is turned by the jack, by means of gearing and a rack which is fastened to the top of the tower.
The cap contains the windshaft and head wheel, which meshes with the wallower on the vertical shaft.
The gearing is then precisely as the post mill, only the vertical shaft is much longer going through several floors to the lower wallower.
The section of the smock mill varies, usually it is an octagon, but occasionally it is a duodecagon.
Fig. 8. Tail winch, Salter's Lode, Cambs.
Previously I have mentioned that the earliest type of mill had to be winded by hand and some of these exist to this day. This primitive way is illustrated in the photograph of the tail pole at Salter's Lode. Fig. 8. The winch is for winding up a chain which is shackled to a series of posts. This operation pulls the tail pole and so rotates the mill.