270 
GUANO AS A MANURE. 
It is so important an article of commerce 
now, that the discovery is, at least, a subject 
of deep interest ; and, perhaps, a short extract 
from this portion of the work may be accept- 
able. The author says,— 
" The use of guano as a manure was first 
mentioned by Inca Garcilaso de la Vega, a 
Spaniard, who wrote on Peru as early as 
1723, in a work entitled Comentarios Realea. 
"'On the sea coast,' says he, 'between 
Arequipa and Tarapaca, in the tract of land 
more than two leagues in length, they have no 
other kind of manure than that afforded by 
sea-birds, which dwell in countless numbers 
on the sea-coast ; they lay their eggs on 
certain islands along the coast, and the quan- 
tity of excrement they leave there is astonish- 
ingly great. At a distance, the masses of 
excrement look like the tops of a range of 
hills. At the time the Incas governed Peru, 
the birds were preserved with great care ; the 
punishment of death was decreed against 
those who landed on the island during breed- 
ing time, or frightened the birds, or at any 
time destroyed them. Each island was a dis- 
tinct province, or, when large, was divided 
into several provinces, over each of which an 
overseer was appointed by the Incas, whose 
care it was to see that every district had its 
due proportion, and no one defrauded his 
neighbour of the universally needed manure.' " 
—P. 6. 
We have some particulars of the chemical 
analysis, in which we are informed of the na- 
ture and properties of guano : the component 
parts, with their several effects on vegetation, 
are very fully detailed, and its comparative 
strength, as estimated by the dung of pigeons, 
is minutely examined, so as to form a con- 
clusion that it is sometimes as powerful when 
used as manure. This will give us some 
notion of how much mischief might be done 
by its careless application, for even pigeon's 
dung is very much too powerful for flowers ; 
and as it was most likely that all who used 
guano would use it in much the same way, 
the destruction of the plants, in all such cases, 
would be inevitable. This, however, only 
makes us regret that Mr. Clark's pamphlet 
was not printed and circulated much earlier. 
That it has, however, done much good ser- 
vice since it appeared, is obvious ; and we 
recommend every body who is likely to use 
the article to procure it and read it carefully 
before they venture to apply the dressing, as 
the only means of becoming acquainted with 
the power and value of it as a manure. The 
author gives a very comprehensive account of 
the various plans by which guano may be pro- 
cured, and holds out hopes that there is suf- 
ficient to supply several generations. The 
report of Jose Villa to the Peruvian Govern-! 
ment is interesting, and may be worth quoting, 
as it is somewhat consolatory, after the com- 
plete clearance of Ichaboe, to find there is 
something to fall back upon for future supplies. 
The report is as follows : — 
" To the State Minister of Finance. 
" Most Excellent Sir, 
" On my arrival at the Chincha Guano 
Islands on the loth instant, I at once, in obe- 
dience to your Excellency's instructions, pro- 
ceeded to make all practical investigation 
respecting them, and I have been enabled to 
collect information which I flatter myself is 
much less incorrect than that which the Go- 
vernment has hitherto had ; and I now pro- 
ceed to lay it before your Excellency. 
" The three Chincha Islands have a rocky 
or granite base, upon which the guano is 
deposited. It is not now necessary to discuss 
whether this substance is an animal produc- 
tion, as its chemical analysis, together with 
the appearance of the islands, prove beyond 
doubt that it is the excrement of the birds 
frequenting them. 
" The quantity of guano on these three 
islands has been very variously estimated. 
Several accounts set down the northern and 
middle islands at one mile in length, whereas 
neither of them is much more than half-a-mile 
in length ; it is not, therefore, surprising that 
calculations thus falsely based should have led 
to inaccurate results. In order to be able to 
present more correct statements, I surveyed 
two sides of each island upon lines forming 
right angles, assisted by a sea compass, a log 
line, and a watch. After having taken the 
dimensions, and made the reductions which 
the irregular shape of the islands required, I 
found upon the three islands a surface equal 
to 1,554,406 square yards. 
" The cutting from which the guano is at 
present taken is in steps or terraces, of which 
the one farthest from the sea is about forty 
yards in perpendicular height, and the others 
together, adding the ascent of the surface of 
each one of them, which is not horizontal, but 
very much inclined, are forty more. But 
there are still more elevated eminences, on 
which the layer of guano must be thicker, as 
the appearance of the islands would lead to 
the conclusion that the granite surface is 
nowhere very high, with the exception of the 
middle island, in which a rocky peak rises 
above the guano. But leaving the excess in 
the higher parts, and twenty yards more to 
compensate both for the peaks which may be 
elevated within the guano and the lesser depth 
of the layer towards the shore, it may be 
taken at a mean thickness of sixty yards, 
which gives an aggregate result of 93,264,360 
