Five Years Progress of Steam Cultivation. 419 
45 lbs. pressure) with a 3 feet driving-slieave will work tlie 
Woolston tackle, at a proportionately slower speed. But Mr. 
Smith acknowledges that " 10-horse engines are the best." 
The reasoning of other persons also is very sound, — that when 
you have a system of anchorage that will stand the strain, 
it is much better to plough 8 acres a day than only 4, for the 
same number of hands engaged ; and though clay farmers in 
Kent and elsewhere may be content with a steam apparatus that 
will turn over 3 acres a day 8 inches deep, because of the ex- 
traordinary value of the tillage on such soil, — yet in a vast many 
other cases, cheapness and expedition are of especial importance : 
on some light lands, indeed, constituting almost all the advantage 
of steam over animal culture. Here the limit of the power of 
the engine seems fixed only by considerations of first cost, and the 
practicability or inconvenience of an enormous weight in a 
country of steep gradients or of soft fields and unsound road- 
ways. Some purchasers of apparatus have exchanged their en- 
gines for others of higher power ; even on a moderate-sized 
light-land farm, we have one employer expressing (in a testi- 
monial to the manufacturer) his regret that he had not bought a 
14-horse engine at first. And some of those who adopted the 
steam grubber at first, simply as an autumn-cleansing auxiliary 
fitted to the old thrashing-engine, have procured a stronger steam- 
horse, extended the wire-rope over the more general tillage of 
the land, and proceeded to work the turn-over plough where it 
was requisite. 
Another point which I cannot dwell upon, but which might 
occupy a large space in an essay on new systems of husbandry 
introduced by the steam-plough, and on the whole economy of 
steam farming, is the management of labour, and the good effect 
of variously arranged piecework in quickening that with which 
the enraged metropolitan sweep upbraided his ass — the " agri- 
cultural pace." 
Long Sutton, Lincolnshire, July, 1863. 
XXIII.— On the Development and Action of the Moots of Agricul- 
tural Plants at various stages of their Growth. By the Rev. 
M. J. Berkeley, M.A., F.L.S. 
Since the publication of Sir Humphry Davy's work on Agricul- 
tural Chemistry, in 1813, no treatise has perhaps had so great an 
influence on the progress of really scientific agriculture as Baron 
Liebig's Letters on Chemistry and Modern Agriculture. Many 
of his conclusions have, indeed, been strongly contested, and his 
observations are often fanciful, if not incorrect ; but even in those 
