114 
ON SKETCHING FROM NATURE. 
[Nature and Art, September 1, 1866. 
beds of coal with which it is associated. We often 
find, too, by the working of the strange and in- 
scrutable laws governing the earth’s chemistry, 
such laws as those by which the pure flint is de- 
posited on the wheat straw and the feathery reed ; 
the morphia to dwell within the juices of the gaudy- 
painted poppy ; the life-saving quina amongst the 
cells and fibres of the “ heart-leaved cinchona,” 
and the deadly strychnia in the vomic nut of 
India, — that casts of extinct creatures, Ammonites, 
and shells of past geologic ages, have been com- 
pletely filled as by molten bronze, with glittering 
sulphuret of iron, accurately filling the space once 
occupied by the living inollusk. Deep buried 
amongst the shale and schist beds, far down amongst 
the slate rocks, and imbedded in the chalk and 
indurated clay, lie these sulphurets. How they 
reached the strange positions in which they are 
found, who can say? Mr. Pepys, in 1811 ( Trans- 
actions of the Geological Society of London , first 
series, vol. i.), was amongst the first to publish a very 
illustrative case of the formation of iron-pyrites from 
the decomposition of the 1 todies of some mice in a 
solution of sulphate of iron. Another illustrative 
instance of the formation of iron-pyrites upon animal 
matter in a decomposing state occurred at the bottom 
of a mine shaft near Mousehole, Cornwall, where a 
dog had fallen into a solution of iron, and its body 
was found surrounded by iron-pyrites. In these and 
other well-known cases the hydrogen evolved from 
the decomposition of the animal matter is considered 
to take the oxygen both from the sulphuric acid 
and oxide of iron, so that the iron-pyrites, or bi- 
sulphuret of iron, is formed. Mr. De La Beche 
thus accounts for the formation of the sulphuret, 
and there is no doubt but that under certain con- 
ditions it might be formed as he states. Yet, when 
we see the most minute and delicate flutings, on 
the surfaces of shells, not thicker than tissue-paper, 
as faithfully moulded in bright shining sulphuret 
as though cast from molten metal by the hands of 
some expert goldsmith, we are rather at a loss to 
understand where, in a structure so delicate, enough 
iron and animal matter can be found to bring these 
strange changes about ; and this, like many other 
secrets of nature — the origin of “ meteoric stones ” 
amongst them, must remain for time and careful 
investigation to elucidate. 
ON SKETCHING FROM NATURE. 
By Aaron Penley, Professor of Landscape Painting at the Royal Military Academy, Woolwich. 
No. 
I T has been my purpose to deviate a little this 
month from the out-door sketching, because I 
am desirous of combining the character of the three 
previous subjects, and so afford to many of your 
readei’S an opportunity of putting into practice the 
several objects before noticed. 
There is in this drawing, scai'cely anything bxxt 
what may be deemed local, and that of such size as 
to give free scope for copying forms with literal 
correctness. I use the term “literal coi'rectness,” 
as rather implying a truthful impression, than that 
elaborated and minute attention to individual detail 
which is now generally understood by the word 
“ Pre-Baphaelitism.” Each portion of the cottages, 
for instance, is to be carefully drawn in with the 
black-lead pencil, showing the various demarcations 
of thatch, wood, and stone. Nothing is more im- 
proving in a manipulative point of view, nor, 
indeed, in an intellectual one, than this kind of 
practice ; for there must of necessity be much thought 
brought to bear on giving to each object and every 
part of it, a veritableness of resemblance, so that 
there can be no mistaking the thing intended. 
Over and over again do I hear the remark, “ I 
thought it was not requisite to dx’aw so much with 
the pencil, when there was colour to be put on.” 
A greater mistake than this there cannot be, for if 
colour has to be used, it is essential that the precise 
position for it should be accurately marked and well 
drawn ; inasmuch as the pencil is often of the 
IV. 
gi-eatest use in keeping up the crispness of outline 
definition. This cannot be too much iixsisted upon, 
it being by the pencil that the first impression has 
to be made and the foundation laid for success in 
after treatment. To each stone there is a form ; to 
each bi-anch there is a form ; to each patch of grass 
there is a form ; the chimney, the windows, the 
thatch, the old broken door, the boat, all have forms 
peculiarly their own; and it is only ixpon a just regard 
to each that they can be presented to the spectator 
in an intelligible and agreeable mannei’, and the end 
be at the same time attained of investing the scene — 
be it what it may— -with a truthful character. I 
fear that some may think I have dwelt almost too 
much upon a cai'eful peiicil outline; but this is of 
such importance to a successful drawing, that it 
were far better I should appear too particular than 
ixot be particular enough ; and I therefore repeat 
that nothing lies nearer the root of failure than a 
vague and hurried outline; while on the other 
hand, an industrious and a carefully studied one, is 
perhaps the greatest ingredient in success. 
The subject for this month’s magazine is given 
with great cleai’ness of form throughout. The light 
and shade, as well as contrast of colour, are suffi- 
ciently pronounced to convey the idea of breadth, 
and at the same time to keep ti’ansparency in every 
part ; that is, to give colour and depth without a 
tendency to blackness. The sky is of a cool grey, 
for the purpose of showing the warm colouring of 
