372 Five Years Progress of Steam Cultivation. 
each other ; the weight of each set being counteracted by separate 
spiral springs coiled in boxes, instead of either wholly or partially 
counterpoised by the weight of the other. And to neutralise the 
tendency of the ploughs to rise out of very difficult work (parti- 
cularly on hilly land), the action of the springs is so adjusted as 
to, lift only a portion of the weight when the ploughs are in posi- 
tion for work, but sustain the entire weight when the set is 
raised into the air. The total length of the 4-furrow implement 
is about 9 yards (the same as of Mr. Fowler's plough). What 
little of its work I have seen is first-rate ; and a high opinion of 
its performance will be found in the Judges'' Report. Of course 
scarifying tines, digging-breasts, or subsoil shares can be substi- 
tuted at pleasure for the clean shares and sweeping mould-boards 
which the Britannia Works are so well able to turn out. 
Before proceeding to notice machinery on the moveable-engine 
system, I would add a word of caution respecting the employ- 
ment of second-hand thrashing-engines for steam tillage. A 7 
or 8 horse engine, Avorking at 45 lbs. pressure, is quite unable to 
perform the work ordinarily expected of a steam cultivator or 
plough. On land where 5+ inch deep ploughing (with a horse- 
plough) gave a fair draught for a pair of horses, Messrs. Morton 
and Harrison found the draught of Mr. Smith's 3-tined grubber, 
when taking 30 inches breadth at a time, 5 and 6 to &\ inches 
deep, to be 12 up to 19 cwts. ; and again, the draught of Messrs. 
Howard's 3-tined grubber, when taking 3 feet breadth, 4 and 5^ 
to 6J inches depth, was 12 up to 21 cwts. At a pace of 3;^ 
miles per hour, these cwts. represent so many horse-power ; far 
beyond the nominal horse-power of the aforesaid thrashing- 
engine. By driving from say a feet sheave, instead of from 
the 5 feet fly-wheel of the engine, the obtainable draught may be 
increased — of course at a corresponding sacrifice of pace in the 
implement and of the acreage done per day. But if the engine 
boiler be sound and strong and the fire-box well strengthened 
with extra " stays," the engine may be safely worked up to 60 
lbs. pressure, giving out proportionally more than her nominal 
power. Engines expressly made for steam cultivation are extra 
strong, capable of working up to double their nominal horse- 
power ; and it is with these that expeditious and therefore cheap 
cultivating and ploughing are accomplished. 
Coming now to moveable-engine forms of apparatus, I will 
first refer to that of Messrs. Coleman and Sons, of Chelmsford. 
The engine travels at intervals along one headland, always 
opposite the end of the work ; and from two coiling drums upon 
a longitudinal axis at the side of the boiler (and unavoidably of 
too small a diameter for the best usage of the rope), two ropes 
are led side by side across the field to two separate and inde- 
