410 
Farming of Cortmall. 
very material. This part of the coast Is beautifully wooded, and 
rich in pasturas^e, while in the vallevs the most delicate plants 
will bloom. But where the granite range decreases in elevation 
to the westward, this difference in temperature is not so per- 
ceptible, for there the ocean-winds sweep across the narrower 
part of the peninsula without any interruption. 
16. Penzance district. — Commencing the survey of the "slate 
formation " at Penzance, joining the granite of the Land's End 
which we have just described, we have a beautiful example of 
fertility of soil proceeding from its mineral composition in con- 
junction with a genial climate. The soil is formed from a mix- 
ture of trappean rocks, chiefly greenstones w ith argillaceous slates. 
Greenstone consists of a mixture more or less intimate of horn- 
blende and felspar, and is distinguished from the granite which 
it frequently joins by the absence of mica and quartz. The pro- 
portion of felspar varies, so that sometimes the greenstones become 
nearly felspar rock, while in other cases they are loaded with 
hornblende, the relative proportion of the latter causing a very 
material difference in the value of the soils produced from their 
decomposition. The following analyses show the chemical con- 
stituents of each : — 
Hornblende. Felsp.ir. 
Silica . . . 47-21 65-21 
Alumina . . 12-18 18-13 
Potash 16-06 
Lime . . .12-73 
Magnesia . .21-86 
Proto-oxide of iron . 2-28 
Fluoric acid . . 1-50 
This soil is an exceedingly rich and friable loam, oftentimes 
deep, and, as we may judge from the minerals which enter into 
its structure, is theoretically — as it is known to be practically — 
perfect. As an example of this, there are occasionally produced 
on it what cannot be realized in any other district in Britain — 
two crops of potatoes in one year — one acre yielding 300 imperial 
bushels of early spring potatoes (see No. 4"2), planted in No- 
vember, and dug up in May and June — a portion of the same 
fetching 'iOs. per imperial bushel in the London market ; and 
after this a crop of late potatoes, planted in .June, and yielding 
400 Imperial bushels per acre. The usual method is first a crop 
of early spring potatoes, after which a crop of turnips. Tlic 
method of cropping in other respects is the same as has been 
already described on the contiguous granite. 
17. From Ilayle to Perranzahuloe, ifc. — Our route avIU now 
extend up the north coast. The soil in this extensive run of 
country is widely contrasted with that which we Lave left, being 
