Report on Implements at Preston. 
701 
the allotment of the prizes, and as most of the exhibitors 
were anxious to have their whippletrees returned to their stands 
for exhibition, we felt hardly justified in retaining them after 
the prizes were adjudged. The excellent rule that prohibits 
the entry of duplicates by any exhibitor might probably be 
relaxed in the case of articles entered " for competition." 
Visitors naturally expect to find such implements at the stands 
of the exhibitors as soon as the Yard is open to the public, 
and the makers suffer if they cannot show them ; at the same 
time it is often desirable that such implements should remain 
in the hands of the Judges or the engineers after the prizes 
are awarded, in order that further investigations may be made 
that may result in obtaining information of general prin- 
ciples of great public value. If our engineers had been able to 
take all the whippletrees to London, and there test them to 
destruction, we should probably have settled the interesting 
question of the comparative merits of wood, iron, and steel for 
the various parts of whippletrees. In the absence of this definite 
information, I offer, with much diffidence, a few non-professional 
observations. 
Whippletrees and pomel-trees should of course be constructed 
to meet the strain to which they are subjected, and the nature of 
this strain is determined by the points of attachment. The fore 
draught is taken from the extremities ; the hind draught is taken 
sometimes from the extremities, as in Figs, i and 2, and some- 
times from the centre, as in Figs. 3, 5, and 6. In the first case, 
the strain is one of compression, as when a man leans his weight 
upon a walking-stick ; in the second, it is a transverse strain, 
as when a man holding the two ends of a stick tries to break it 
across his knee; while in Fig. 11, the transverse strain cor- 
responds to the effect of bending the stick across two knees. 
Ash and tubular iron were the only substances subjected to the 
strain of compression. Solid wrought iron subjected to such a 
strain has little more than three times the strength, though it is 
eleven times the weight of ash. Even when used in a tubular 
form its greater weight and cost are hardly counterbalanced by 
its greater durability. 
When subject to a transverse strain, solid wrought iron of 
similar section is four times as strong, while eleven times as 
heavy as ash. In Mr. Corbett's entries, in Classes V. and \ II. 
(see Fig. 6), we find ash and solid rolled steel subject to trans- 
verse strain in the same set of whippletrees ; and it is a very 
curious fact that while rolled steel is used for the minor strains, 
the main pomel-tree is shaped of ash in the old and simple 
fashion adopted by many farmers who have their whippletrees 
made at home by the village carpenter. Singularly enough, 
