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Example 52, fig. 55, is a transverse vertical section of the * patent conical flour-miiy of which the perspective view is given in

fig. 55.

Example 53, fig. 56.

Mechanical Drawing Example

Example 54, fig. 57, is front elevation of a fixed high-pressure steam-engine.

fig. 57.

Example 55, fig. 58, is a perspective sketch of a fire-engine.

Mechanical Drawing Example

Example 56, fig. 59, ia a side elevation of a ' disc-pump.'

Mechanical Drawing Example

Example 57, fig. 60, is a perspective sketch of a ( drug-grinding-machine.'

Mechanical Drawing Example

Example 58, fig. 61, is the side elevation of an' American wood-burning locomotive.'

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In the various examples we have given, the pupil will see the method in which the various parts are shaded in order to represent round parts, fiat, and so on. Mechanical outline-drawings may be shaded by means of lines, as in the examples we have given, thus imitating the manner in which engravers give the appearance of desired shade. When this is carefully executed in fine ink lines, regularly drawn, the drawing has a fine effect when finished, accurately presenting the appearance of roundness in some portions, and flatness in others, according as the subject requires. When this method is considered too tedious, the shades may be put in with Indian ink and a camel-hair brush, the appearance of roundness being imparted by first putting in a part of uniform depth in tint, and washing the outside line of this with a brush moistened in pure water, until the colour gradually blends into the tint of the surrounding paper. The depth of tint towards the outside part should be gradually got up to the desired point by repeated operations, the colour used being of a light shade. The addition of a little blue imparts a softness to the Indian ink, which is agreeable to the eye. Cast-iron surfaces are represented by a bluish-grey tint, malleable iron by a light blue; brass surfaces by a faint yellow, brick by a reddish yellow, faintly mottled with a shade darker of the same colour; stones by a faint yellow, with horizontal streaks of a darker tint; wood by yellow, with vertical streaks of a faint black; water by faint blue, with horizontal stieaks or lines of a faint black: these look best when put in carefully with the pen and square, as in the diagram in fig. 62. These are the principal shades of colours required in mechanical drawings. The colours generally required are Indian ink, gamkoge, Prussian blue, Indian red, lake, and sepia.

The reader desirous of extending the range of his copies will find numerous excellent examples of machinery in the work on Mechanics in this series.

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