ENGINEER AND MACHINIST’S DRAWING-BOOK.
In Fig. 8, the smokebox-tubeplate is shown, with its
fixings to the other plates of the smokebox, and to the
hind ends of the cylinders. The tubes are all set out,
also the steampipe and boiler-stay fixings. The fore end
of one of the leading side springs is drawn in section, to
show how the spring and the smokebox are adjusted to
clear each other; the spring is shown otherwise in Fig. 2.
The bolt-fixings for the hind ends of the cylinder-castings
are shown in the same way as for the fore ends.
The firebox is shown in working detail in Figs. 4, 5.
The form of the firebox, with its midfeather, and the fire-
box-shell, are fully shown ; also the position of the stay-
bolts between the firebox and the shell, and the position
and detail of the roof stays and the longitudinal tie-rods.
The seat for the safety-valve is shown at the crown of the
shell, and the lateral brackets by which the firebox-shell
is supported by the frameplates. The position and fixings
of the ashpan are also indicated. In short, everything
affecting or affected by the firebox and its shell, is
represented; and the drawing, like that of the smokebox,
is complete for the use of the workman.
It will have been observed, in these details of the boiler,
that many of the fixings are set out by merely drawing
down their principal bolt or bolts. Sometimes, the posi-
tions of rivets or bolts are given by their centre lines only,
if seen laterally; or by sections of the bolts with crossed
lines, or crossed lines only, if seen on end, the intersections
of the lines being the centres of the rivets or bolts. Thus
simplicity and explicitness are combined.
The necessary working dimensions are also marked on
the drawings. Dimensions should never be omitted in
drawings intended for use, whether done full size, or to
any smaller scale. Some little arrangement is necessary,
so as to have a sufficiency of written dimensions, distinctly
arranged, and without superfluity.
The detail of the motion-plate and its connections,
shown in half-elevation, Fig. 6, shows how large frame-
surfaces may be represented, and how the positions and
forms of various perforations or attachments may be set
out upon them. The external boundary of the plate is
deepened with a fringe of tinting within the line. The
openings made in the plate, to clear the connecting rod and
the valve-gear, are lightly tinted, to bring out their forms,
and the limits of the play of the mechanism are shown
respectively by sections of the connecting-rod and the
upper and lower eccentric-rods. The positions of the
brackets to carry the guidebars are also clearly defined
by strengthening the outlines of the bracket-soles with
an interior border of tinting, as is done for the plate
itself. The attachments of the feed-pump, the brackets
joining the motion-plate to the frameplates, and the
angle-irons joining it to the boiler, are also shown ; and,
in all cases, the positions and sizes of the bolts and rivets
are shown by sections and centre-lines.
The details, Fig. 7, of a portion of the valve-gear, illus-
trate the treatment of rather intricate pieces of mechanism.
There is no attempt to show the parts in their actual
relative positions, as they are too closely mixed to render
it desirable; but they are freely dissected and laid out, so
that each of the members may be fully and plainly repre-
sented. The figure represents the intermediate levers,
hanging from the barrel of the boiler, and their imme-
diate connections. The neighbouring guide-bars pertaining
to the cylinders, are introduced, to show the space available
transversely for the arrangement of the valve-gear. The
relative positions of the eccentrics are indicated ; and the
centre-lines of the parts of the gearing are laid down with
precision, and their relative positions are figured.
The detail of the wheel, Fig. 8, is an example showing
how, by a judicious selection, the whole may be repre-
sented by a part. The body of the wheel is of cast-iron,
and the tire is of wrought-iron ; and the partial elevation
in section, comprising the whole preparation for the recep-
tion of the crankpin, together with the partial transverse
section of the wheel, and the two smaller sections of the
spokes, illustrate the construction completely.
The detail of the connecting rod, Fig. 9, is a fine speci-
men of detail drawing. The elevation is half external,
and half in section, and, with the plan, shows everything
High Pressure Steam Engine, of Six Horse-power.
The plates before us contain an example of the compact
class of steam-engines, known as the “ Table-engine,”
made by Robert Napier of Glasgow; comprising a com-
plete set of general and detail drawings, useful not only
as examples of elaborately-shaded drawings of machinery,
but also as drawings elaborately figured. They are well
suited for the portfolio of a drawing-office, to be kept in
store for reference, as they contain all the materials for
the preparation of regular workshop-drawings, of which
examples have been given in the plates immediately
As this is not a treatise on the steam-engine, but a
treatise on drawing, the following enumeration of refer-
ences will suffice:—
Plate XXXVII. Side Elevation.
Plate XXXVIII. End Elevation.
Plate XXXIX. Sectional Elevation.
Plate XL. Plan.
Details:—Figs. 1-5, Parts of the governor.
Figs. 6-10, Throttle-valve and connecting gear.
Plate XLI. Details:—Figs. 11-14, Steam-cylinder, valve-chest, and
Figs. 15, 16, Stuffing-boxes for piston-rod and valve-rod.
Figs. 17, 18, Plummer-blocks for crank-shaft and traverse-
Fig. 19, Force-pump.
Plate XLII. Details:—
Figs. 20, 21, 22, 24, Soleplate, columns, and entablature.
Fig. 25, Guides for crosshead.
Fig. 23, Fly-wheel.
Figs. 26, 27, Crankpin and crank.
Fig. 28, Lower part of connecting-rod.
Figs. 29, 30, Piston and packing-spring.
Figs. 31, 32, Eccentrics to drive valve-gear and foreepump.
Figs. 33, 31, Governor-brackets.
Fig. 35, Crankshaft.