ENGINEER AND MACHINIST’S DRAWING-BOOK.
shop contains the whole of the machinery and tools for
engine-work. The engine is placed at one end, and motion
is derived from it through lines of shafting properly
arranged along the shop ; it is also conveniently placed
for working the tools employed in the boiler-shop immedi-
The smithy is equal in width and height to the fitting-
shop, but is 21 feet shorter, to make room for the brass
foundry, being about 154 feet long. It contains fifteen
hearths, which are ranged along the walls, and placed
generally at 15 feet centres.
The boiler-shop, 42 feet wide by 86 feet long, and
18 feet high, is placed behind the erecting and fitting
shops; the grindery, 42 feet by 43 feet, is placed in the
angle of the boiler-shop and smithy, and completes the
block of buildings set apart for the heavy work.
The brass-foundry as already stated occupies a plot of
ground at the other end of the smithy, and is 20 feet
wide, by 42 feet.
The enlarged sections of the walls and footings, attached
to the plan, explain their formation and show how the
flooring is laid in.
To the left, the greater part of the building is occupied
by the carriage repairing shop, which is 129 feet 7 inches,
or about 130 feet wide, by 175 feet 6 inches long, and is
for the greater part 18 feet high. It is divided longitu-
dinally into two equal parts, about 57 feet wide, separated
by a central space for the traverser, 15 feet wide. In each
division there are eleven lines of, rails, making in all
twenty-two lines, placed at 15 feet centres, each of them
capable of receiving two carriages conveniently, or three
waggons of moderate length. Three of the outer lines
of rails are set apart for receiving and turning out the
vehicles, and have corresponding gateways; and by means
of the traverser in the middle of the shop, the vehicles
may be shifted to or from any part of the shop without
interfering with those already under cover.
An upper flat, 42 feet wide, is built over the outer part
of the carriage-shop, of the whole length, for the finer
repairs of the carriage-stock.
The saw-mill and timber store is 86 feet long and
42 feet wide, and is built against the end of the carriage
repair shop. The carriage smith and spring shop stands
next the saw-mill, it is 42 feet by 43 feet, and completes
the block of buildings arranged for the lighter class of
work pertaining to carriages and waggons.
In the interval, 84 feet, between the two main divisions
of the works, the heavy smithy is placed. The smithy is
84 feet long and 42 feet wide, and contains four hearths and
one steam-hammer. Behind the smithy, are the furnaces
and boilers required for the uses of the works, roofed over
with corrugated sheet-iron; and in the distance is the
chimney, to which the flues from the furnaces are led
under ground. The chimney is 4 feet 3 inches square
inside at the bottom, 4 feet diameter at the top, and
90 feet high from the ground line. The base of the
chimney is 15 feet 6 inches square, and is carried at least
15 feet below the ground-line. It rests upon a timber
platform 16 feet 6 inches square, placed on piles and on
a bed of concrete 17 feet 6 inches square.
The walls and partitions of the building are of brick,
so also is the chimney. The floors are of timber, and the
upper floors over the carriage shop are carried upon cast-
iron columns. The roofing is of timber, and is detailed
in Plate XLIX. The doors also are of timber.
The engravings are very fully figured, and illustrate
very completely the manner in which working drawings
of work-shops are got up.
THE PROJECTION 0E SHADOWS.
Light is diffused through space in straight lines, and the
lines of light are called rays. When the source of light
is situated at a very great distance from the illuminated
objects, as in the case of the sun with relation to the earth,
the rays of light do not sensibly diverge, and may be re-
garded as exactly parallel to each other. Such is the case
in mechanical drawings, where the objects to be represented
are always regarded as illuminated by the solar light.
Light is called direct when it is transmitted to an
object without the intervention of any opposing medium.
But as all bodies subjected to the action of light possess,
in a greater or less degree, the property of giving out a
certain portion of it to the surrounding objects, this
reflected light becomes in its turn, though with greatly
diminished intensity, a source of illumination to those
objects which are deprived of direct light.
Everything which tends to intercept, or prevent the
direct light from falling upon a body, produces upon the
surface of that body a degree ot obscurity of greater or less
intensity; this is called a shade or shadow. Such effects
are usually classified as direct shadows, and cast shadows.
The shade proper, or shadow, as we shall simply
call it throughout this treatise, for the sake of con-
ciseness, is that which occurs on that portion of the
surface of a body which is situated opposite to the en-
lightened part, and is the natural result of the form of