Mechanical drawings are -delineated in three ways; as 1 plan,1 shewn in Example 41, fig. 44, which represents the 'plan' of a pulley or solid drum. In * elevation,' as in

Example 42, fig. 45, which is the elevation of fig. 44. Elevations may be ' front,' 1 back,' ' end,' or 1 side/ In 1 section,' as in

Example 43, fig, 46, which is a transverse vertical section of figs. 44 and 45. The same letters of reference denote the same parts in these three sketches. Sections may be divided into 1 transverse' and < longitudinal,' these being either vertical or horizontal.

In finished outline-drawings shadow-lines are made use of. The light, in the generality of examples, is supposed to come from the. top and left-hand side of the drawing, thus throwing the right hand and under lines.

in shadow. These are therefore made darker in inking-in the drawing, as exemplified in

Example 44, fig. 47, which is the outline drawing of * front elevation of high-pressure steam-engine,' the plan of sole-plate of which is given in

Example 45, fig. 48.

We now proceed, as a conclusion to this department, to give a few examples to serve as copies to the student, in copying which he will find his operations much facilitated if he has paid fiill attention to the preliminary lessons. Those copies in perspective are all set out by the rules given in the section on ( Perspective' in the Illustrated London Drawing^ Book, to which prefer the reader.

Example 46, fig. 49, is a transverse vertical section of Nasmyth's steam ventilating-fan.

Example 47, fig. 50, is a longitudinal vertical section of an aerated water-machine.

fig. 50.

Example 48, fig. 51, is a longitudinal and transverse vertical section of a smoke-burning furnace.

Example 49, fig. 52, is (side elevation' and ' end elevation' of Roberts' Alpha clock.

Example 50, fig. 53, represents a side elevation of a corn-mill, with section (vertical) through the grinding-plates.

Example 51, figĀ» 54, isa perspective view of another form of portable corn-mill.

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