The first thing to be done on unpacking our specimens is to pick out
those which require the least attention, and get them out of the way.
These will be your rock specimens, which, if they have been trimmed
properly in the pit, will not need much further manipulation; a word or
two, however, as to the best method of proceeding when it is desirable
to reduce a specimen, will not be out of place. If you wish to divide it
in two, or detach any considerable portion, the specimen may, while held
in the hand, be struck a smart blow with the hammer; as, however, it not
frequently happens that even with the greatest care the specimen under
this treatment breaks in an opposite direction to that required, it is
advisable to adopt a somewhat surer method, namely, to procure a block
of tough wood, and in the centre bore a hole just large enough to
receive the shank of the cold chisel, and thus hold it in an upright
position with the cutting edge uppermost; placing the specimen on this,
and then hitting it immediately above with the hammer, it may be
fractured through in any required direction. To trim off a small
projection, hold the specimen in your hand with the corner towards you
and directed slightly downwards, then with the edge of the striking face
of the hammer hit it a smart blow at the line along which you wish it to
break off; the object of inclining the specimen is to make sure that the
blow shall fall in a direction inclined away from the portion you wish
to preserve, a _modus operandi_ which it is necessary to bear well in
mind if you would not spoil many a choice specimen. Anything beyond very
general directions, however, it is impossible to give in such matters as
this: experience, and a few hints from those who have themselves had
practice in collecting and arranging specimens, are worth more than any
written description, however lengthy and elaborate.
Having reduced your specimen to the required size and shape, the next
thing to be done is to write a neat little label for it--the smaller the
better--stating, first the nature of the specimen, secondly the
geological formation to which it belongs, thirdly the locality from
which it was procured, and fourthly the date when acquired, thus--
Limestone.
Lower Carboniferous.
Quarry, 1 mile N.W. of ----
21. 8. 8-.
ruling a neat line at the top and bottom (red ink lines give a more
finished appearance than black). When the label is dry, damp it to
render it more pliant, and gum it on to the flattest available surface
of the specimen, pressing it well into any small inequalities that it
may hold the firmer. A small quantity of pure glycerine (about an eighth
part) should be added to the gum before use, in order to prevent its
drying hard and brittle. The specimen is now ready to place in its tray
and be put away in the cabinet.
In the next place, pick out the fossils which you obtained from the
limestone. With the cold chisel set in its block of wood, and the
trimming hammer, remove as much of the surrounding rock (_matrix_) as
you can without damaging the fossil, and with a smaller chisel any
pieces that may be sticking to and obscuring it. Fossils in soft
limestone, such as chalk, are best cleaned with an old penknife, and
needles fixed into wooden handles, and finished off by the application
of water with a nail-brush. Should you have the misfortune to break any
specimen in the process of trimming, it should at once be mended. The
most effectual cement for this purpose is made by simply dissolving
isinglass in acetic acid, or, where the specimen contains much iron
pyrites, and there would be a danger in starting decomposition, shellac
dissolved in spirits of wine. When, however, neither of these are handy,
chalk scraped with a penknife into a powder, and mixed with gum to the
consistency of a thick paste, answers admirably. Failing this, however,
gum alone will frequently suffice.
The next thing is to place the like kinds together in their several
trays, writing a label, as before, for each tray, but leaving a blank
space at the top for the insertion of the name when ascertained. The
commoner sorts may be named from the figures of them given in the
text-books (see list at the back of the title page); but failing this,
it will be the best plan to seek the help of any friends who have
collections, or to take the fossils to some museum, and compare them
with the named specimens there exhibited. The label may be laid at the
bottom of the tray with the fossils loose on the top of it, each fossil
being marked with a number corresponding to one on the label. Another
plan is to fasten the label by one of its edges to the side of the tray;
or, if the fossils are small and mounted on a piece of card fitting into
the tray, it may be gummed with them to the card.
Now let us take the shells we obtained from the dark-blue clay, with
those and the bones from the old river bed up above. Gently turn them
out of the tins, in which they were packed in the quarry, on to a paper
or the lid of a card-board box, and with a pair of forceps pick them
carefully out of the bran, and place them in large shallow trays, taking
care not to mix those from the different beds. As we found when
collecting them, these shells are extremely brittle from loss of animal
matter, and our first object is therefore to harden them by some
process, so that they will bear handling. To accomplish this you must
get a saucepan, one of those wire contrivances for holding eggs when
boiling, or a big wire spoon, such as formerly was used for cooking
purposes, a packet of gelatine, and some flat pieces of tin, which last
are easily procured by hammering out an old mustard or other tin, having
previously melted in a gas flame the solder wherewith it is joined. Half
fill the saucepan with clean water, and put in as much gelatine as when
cold will make a stiff jelly; melt this over the fire, placing the
fossils meanwhile in a warm (not hot) corner of the fire-place; then
when the gelatine is quite dissolved, pile as many of them, whole or in
pieces, into the egg-boiler, or spoon, as it will contain, hold them for
a second in the steam, and then lower them gradually into the hot
gelatine until it completely covers them. Little bubbles of air will
rise and float on the surface. As soon as these cease to appear, raise
the fossils above the surface and allow them to drip; then pick them up
one by one with the forceps, and spread them out on pieces of tin before
the fire, but not too close to it. As soon as their exterior surfaces
become dry, and before the gelatine gets hard, they should be taken up
(they may be handled fearlessly now), and the superfluous gelatine
sticking to the surface gently removed with a camel's-hair brush dipped
in clean warm water; otherwise, when dry, they present an unnatural
varnished appearance, and have a tendency, on small provocation, to
become unpleasantly sticky.
Small bones may be treated in like manner, but for large ones, weak glue
is to be preferred to gelatine, which is only suitable for the finer and
more delicate objects. Where it is desired to harden only a few things,
it is better to mix the gelatine in a gallipot, which can be heated when
required by standing it in a saucepan of water on the fire. In any case
the gelatine need never be wasted, as it will keep almost any length of
time, and can therefore be put by for future use. In default of the
egg-boiler or wire-net spoon, an equally useful plan is to make a
strainer from a piece of perforated zinc by turning up the edges all
around, and attaching copper wire to it by which to lower the fossils
into the gelatine, and raise them again.
When the fossils are quite dry they can be sorted, and those which have
come to pieces may be mended with diamond cement (_i.e._ isinglass
dissolved in acetic acid), and then properly labelled and placed in
trays, or mounted as previously described.
To the plant remains and Lignite there is little that can be done beyond
trimming them to suit the trays. Should there be much iron pyrites in
the Lignite, it is sure, sooner or later, to decompose, when all that
can be done is to throw it away. In the case, however, of valuable
fruits and seeds, such as those from the London Clay of Sheppey, it is
worth while to preserve them, if possible, in almost the only way known,
viz. by keeping them in glycerine in wide-mouthed stoppered bottles, or
by saturating them with paraffin.
Having prepared the specimens for the cabinet, the next thing is to
arrange them in proper order. There are several ways of doing this, but
for those who have not had much experience the following plan will be
found the best:--Group the specimens according to the formations to
which they belong, and arrange these groups in proper sequence (_vide_
Table, p. 16); then take each group, and arrange the specimens it
comprises in columns. Beginning at the top of the left-hand corner,
place first the specimens of the rock itself, and under it any examples
of minerals, concretions, etc., found in that rock; next the fossil
plants, if any; and finally, such animal remains as you have arranged
according to their zoological sequence, beginning with the lower forms
(_vide_ Table, p. 32). Unless cramped for room, each formation should
begin a new box, its name being written on a slip of paper and placed at
the head of the columns of trays. A label setting forth its contents
should be fixed outside each of the boxes, which can then be put away on
your cupboard shelves.
TABLE OF THE PRINCIPAL FOSSILIFEROUS STRATA ARRANGED IN CHRONOLOGICAL
ORDER.
_Land Plants._-----------+
_Invertebrata._--------+ |
_Fishes._------------+ | |
_Amphibia._--------+ | | |
_Reptiles._------+ | | | |
_Birds._-------+ | | | | |
_Mammalia._--+ | | | | | |
_Man._-----+ | | | | | | |
| | | | | | | |
| | | | | | | |
{Alluvial Deposits, | | | | | | | |
_Quaternary, { River Valley | | | | | | | |
or { Gravels and | | | | | | | |
Pleistocene._ { Cave Deposits. | | | | | | | |
{Drift and Glacial | | | | | | | |
{ Deposits. V | | | | | | |
| | | | | | |
_Cainozoic, {Pliocene. | | | | | | |
or {Miocene. | | | | | | |
Tertiary._ {Eocene. | | | | | | |
| | | | | | |
{ {Chalk. | | | | | | |
M { _Cretaceous._ {Upper Greensand. | | | | | | |
E { {Gault. | | | | | | |
S { | | | | | | |
O { _Neocomian._ {Lower Greensand. | V | | | | |
Z { {Wealden. | : | | | | |
O { | : | | | | |
I { { {Purbeck. | : | | | | |
C, { {_Upper._{Portland. | : | | | | |
{ { {Kimmeridge Clay. | : | | | | |
or { { | : | | | | |
{ { _Mid._ {Coral Rag. | : | | | | |
S { { _Oo- { {Oxford Clay. | : | | | | |
E { {lites._{ | : | | | | |
C { { { {Cornbrash and | : | | | | |
O { { { { Forest Marble. | : | | | | |
N { _Jurassic._{ {_Lower._{Great Oolite. | : | | | | |
D { { { {Fullers' Earth. | : | | | | |
A { { { {Inferior Oolite. | : | | | | |
R { { | : | | | | |
Y { { Lias. | : | | | | |
| : | | | | |
{ {Trias, or New | : | | | | |
P { _Poikilitic._ { Red Sandstone. V ? V | | | |
A { {Permian. | | | |
L { | | | |
AE { {Coal Measures. V | | |
O { {Millstone Grit | | |
Z { _Carboniferous._ { and Yoredale | | |
O { { Rocks. | | |
I { {Carboniferous | | |
C, { { Limestone, etc. | | |
{ | | |
or { Devonian and Old | | |
{ Red Sandstone. | | |
P { | | |
R { {Ludlow Beds. | | |
I { {Wenlock Beds. | | V
M { _Silurian._ {Woolhope Beds. | |
A { {Tarannon Shale. | |
R { {Llandovery or May | |
Y. { { Hill Group. V |
{ |
{ {Bala and |
{ { Caradoc Beds. |
{ {Llandeilo Flags. |
{ {Arenig Group. |
{ _Cambrian._ {Tremadoc Slates. |
{ {Lingula Flags. |
{ {Menevian Beds. |
{ {Longmynd and |
{ { Harlech Group. V
{ :
{ Pre-Cambrian and :
{ Laurentian. ?