leton from the rock he will need to keep ever in mind the form and
relations of each bone, the picture of the skeleton as it may have
been when buried. The heavy ledges above are removed with pick and
shovel, often with help of dynamite and a team and scraper. As he gets
nearer to the stratum in which the bones lie the work must be more and
more careful. A false blow with pick or chisel might destroy
irreparably some important bony structure. Bit by bit he traces out
the position and lay of the bones, working now mostly with awl and
whisk-broom, uncovering the more massive portions, blocking out the
delicate bones in the rock, soaking the exposed surfaces repeatedly
with thin "gum" (mucilage) or shellac, channeling around and between
the bones until they stand out on little pedestals above the quarry
floor. Then, after the gum or shellac has dried thoroughly and
hardened the soft parts, and the surfaces of bone exposed are further
protected by pasting on a layer of tissue paper, it is ready for the
"plaster jacket." This consists of strips of burlap dipped in
plaster-of-paris and pasted over the surface of each block until top
and sides, all but the pedestal on which it rests, are completely
cased in, the strips being pressed and kneaded close to the surface of
the block as they are laid on. When this jacket sets and dries the
block is rigid and stiff enough to lift and turn over; the remains of
the pedestal are trimmed off and the under surface is plastered like
the rest. With large blocks it is often necessary to paste into the
jacket, on upper or both sides, boards, scantling or sticks of wood to
secure additional rigidity. For should the block "rack," or become
shattered inside, even though no fragments were lost, the specimen
would be more or less completely ruined.

[Illustration: Fig. 41.--A Dinosaur skeleton, prospected and ready
for encasing in plaster bandages and removal in blocks.
(_Corythosaurus_, Red Deer River, Alberta.)]

The next stage will be packing in boxes with straw, hay or other
materials, hauling to the railway and shipment to New York.

Arrived at the Museum, the boxes are unpacked, each block laid out on
a table, the upper side of its plaster jacket softened with water and
cut away, and the preparation of the bone begins. Always it is more or
less cracked and broken up, but the fragments lie in their natural
relations. Each piece must be lifted out, thoroughly cleaned from rock
and dir