The Evolution of Agricultural Imflements. 247 
introduced into this country by Riches and Watts in 1857, be- 
came a model for the well-known, and now widely-distributed, 
Barford and Perkins’s gristing-mill. 
The Royal Agricultural Society’s Trials at Plymouth in 1890 
may be regarded as an attempt to select from among modern 
improvements upon the systems of grinding above described 
that which is best fitted for a farmer’s use ; and, having regard 
strictly to this problem, the experiments gave no uncertain 
sound in declaring that flat metal discs have the greatest general 
adaptability for grist-milling, while they are economical of power 
and time, produce good feeding samples, and are cheaper, both 
in first cost and renewals, than any other mills. 
Chaff-cutters. — The cutting of hay or straw into short lengths 
does not greatly facilitate digestion, for whatever material 
of this kind is eaten by a ruminating animal is pretty sure 
of undergoing this process whether cut or not. It is only 
because chaff-cutting facilitates the admixture of more nutritious 
matter with hay or straw that its use has become universal. 
Three different principles of construction have struggled for 
existence in the chaff-cutter. In Salmon’s, Passmore’s, and 
Clj’burn’s machines, dated respectively 1797, 1804, and 1840, 
spiral cylindrical knives were employed, giving either an inter- 
mittent or continuous cut. In Gillett’s machine, dated 1846, 
an oscillating knife moved vertically up and down in guides 
like the blade of a guillotine, whence this implement took its 
name. Finally, in Cornes’s machine, first shown in 1847, the 
knives were arranged radially, cutting from the centre outwards, 
as they do in all the chaff-engines of the present day. 
Later improvements have consisted chiefly in details of con- 
struction ; in the application of the chaff-cutter to the threshing 
machines, whereby the straw is cut and bagged as fast as it 
issues from the straw-shaker ; and in the addition to these 
machines of arrangements by which, should the feeder get 
caught in the feed-rolls, his body, being drawn forward, presses 
against a lever which throws the machine out of gear, and 
ensures the man’s safety. 
Turnip cutters are remarkable for the fact that they have 
remained absolutely unchanged since their first introduction by 
Gardner of Banbury, now more than fifty years ago ; while — 
Oil-cahe breaJcers, used by Coke of Holkham and the Duke 
of Bedford before the commencement of the present century, 
consist of a pair of serrated discs working into one another, but 
have no mechanical features of interest to describe. 
Gorse mills are a modern invention for the reduction of furze 
to a pulp soft enough to be mixed with the food of dairy cows. 
