616 Report on the Trials of Combined Stacking-Macliines 
use of tlie column that had been thus headed. No previous in- 
timation liad been given to the makers of any standard height 
that might correspond to the horse-power among steam-engines, 
by which engines of the same nominal horse-power are tested 
against each other. The fairest method that occurred to us was 
to determine first what height would be considered satisfactory 
on the majority of farms throughout the kingdom, and then to 
give the machine that delivered to that height such marks as 
would leave a small margin of advantage to machines fitted to 
build stacks of the exceptional size that may be seen on a few 
farms in Lincolnshire and elsewhere. 
In future, it might be well to offer prizes for elevators that 
will raise hay to some specified height. 
In this trial it was assumed that a clean delivery of 25 feet 
high would meet the present requirements of most farms. As the 
use of elevators extends, the average height of our stacks may 
perhaps increase ; but the maker who succeeds at 25 feet will 
generally be able to execute an order satisfactorily for a machine 
to deliver at 30 feet when needed. 
In column 10 it will be noticed that six out of the fifteen ele- 
vators were provided with plain octagonal chain-wheel driving 
chains formed of long riveted links, varying from 5f to 1^ 
inches from rivet to rivet. Among these six are found all the 
three machines that gained full marks in column 27 for 
completeness of delivery. As each of these long links leaves 
the upper octagonal wheel on its return journey, the joint 
of the rivet is straightened out with a sudden, slight jerk, which 
helps to shake off all hay or straw from the rakes ; other chains 
with small links come off so smoothly from the upper wheels 
that straw and hay often remain hanging upon them. Two other 
machines (5527, Robson, and 5014*, S. Lewin) also had chains 
formed of long links, but in these cases the octagonal wheels were 
furnished with large teeth. Four of the machines, viz. the first 
three and the sixth on the list, were furnished with a chain com- 
posed of small links of steel wire. No. 6 gauge, turned over in 
hook shape, but not welded ; these were driven by a chain-wheel 
with a notched groove. All chains are more apt to slip on the 
driving-wheel when the trough is high than when it is low ; 
when the trough is quite horizontal the lowest point of the 
chain will be in the middle, at an equal distance from either 
wheel ; but as the trough is gradually raised, the curve in the 
under side of the ladder-chains is brought nearer and nearer to 
the lower (driving) wheels ; if there is much slack, or if the 
links are small, they will soon begin to slip round the wheels. In 
the description of Messrs. Taskers' elevator (No. 4841), there is 
pointed out a very ingenious and effective method of artificially 
