Five Years Progress of Steam Cultivation. 379 
ing; and foldin<r of sections of the link-cliain for removal in a 
cart, instead of quickly and conveniently coiling it upon the 
engine-drum. Again, the chain cannot ride upon porters, owing 
to the excessive amount of play or hinge-action so demanded of 
the rivet-and-plate joints; hence incurring a very considerable 
waste of motive power. The comparative draught of a given 
length of this link-chain and of wire-rope trailing upon the 
ground has not been ascertained ; but the weight of the present 
link-chain is 3 lbs. per lineal yard, or from one-half up to twice 
more than that of the wire-rope of different sets of apparatus. 
Of course, it is a mere sophism to excuse the heavy drag of a 
rope or chain along the ground by saying that a cwt. or so more 
coal per day will give the extra power required. For when an 
engine is already working up to her full power compatibly with 
safety, an additional one, two, or three horse-power can be ob- 
tained only through a stronger boiler, a larger cylinder, and in 
fact, by an entire engine of bigger dimensions and higher prime 
cost. 
As applied to the twin-engine system, Mr. Hall's traction- 
medium deserves consideration. Instead of two 12 or 14 horse 
engines, each idle in turn while the other is hauling a single 
length of rope, he employs two 6 or 7 horse engines, both simulta- 
neously hauling an endless link-chain, and thus accomplishing 
as much work as engines of double the power, weight, and first 
cost. The back, or return ply of the chain being always tight, 
can be mounted upon low porters ; and the other ply along the 
track of the plough may be similarly upheld where in advance 
of the implement, though left upon the land where running slack. 
For varying lengths of furrow, a portion of spare chain is carried 
folded upon the implement ; a hook that will lay hold of the 
chain at any point allowing one or more links to be left out or 
taken up at pleasure. I do not know why Mr. Fowler's twin- 
engines should not be of lower power, and work an endless wire- 
rope with clip-drums ; thereby lightening the apparatus for a 
deep and sticky district, as well as sparing the contract proprietor 
or company several hundred pounds of purchase-money. The 
objection to two engines working at once is the difficulty of 
securing simultaneous starting and stopping : it remains to be 
seen how far this may be overcome, — perhaps by signal rope 
laid out between one engine and the other. 
My account of the steam-tilling machinery at Worcester being 
intended to touch only upon points not fully elaborated in the 
Judges' Report, I leave all details of the four days' competitive 
field-work, merely drawing certain inferences, either from my own 
personal observation or from the official statistics and remarks. 
Comparing self-locomotive apparatus Avith that working a com- 
