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Fig. 147.

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will be on an angle of 45 degrees, such as the dotted line shows in the sketch.

Having put in this line, which should be done in light pencil, the centers for striking the curves of the several ells may be taken on this line.

In taking up much of the work considered in this article, we are not adhering strictly to the requirements of the plumber, but as the work of the plumber and fitter are so closely allied, this work will prove of value to the average plumber we believe.

Our readers will find plenty of good practice work in the illustrations which we have presented in this chapter, and the drawing of valves, radiators and coils will be found of special value.

Fig. 146.

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Jo Raat

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Jo Raal

CHAPTER XXVI
HE showing of steam pipes on while B is obtained by looking downward

floor plans is a matter that calls from the left. Either of these two views
for attention, and in this con- is very common, much more so, we may

nection we give Figs. 148 and say, than views obtained by looking up149. The method shown in Fig. 148 is ward upon the object. C shows a conthe one which is probably most used, the nection which is viewed from the left pipes being represented by single lines, and on a level with it, instead of downand the risers by circles.

ward or upward, and occasionally is a The other method shown in Fig. 149 desirable method to follow. D shows a has the advantage of showing the connec- little more difficult perspective than those tions of branches with the main, more in preceding, and E shows valves in two difdetail than the method just mentioned. ferent positions, in perspective. A glance at the sketch will show that the A close study of these examples of pertee on the main is turned at 45 degrees, spective will show that the ellipses which

are seen on the fittings are square with the direction of the pipe, no matter in what direction the pipe may run.

Compare F and G, which are supposed to represent the same thing. The ellipses in F are not square with the fitting or pipe, while those in G are. The result is apparent. The tee in F is distorted, while that in G is not.

If our reader will hold a piece of pipe in front of him with the end pointing

toward him, that end will appear as a full Fig. 148.

circle, but if he will turn the pipe from and a 45-degree ell · brings the branch

this position gradually until it stands level again.

lengthwise instead of endwise, this circle Now we come to the matter of showing

will become an ellipse, gradually narrowpiping in perspective, the last point

ing, until finally, when in a position which we shall take up in this series.

lengthwise, no part of a circle or ellipse It is of much importance, for it will be

is to be seen, simply the square end befound that it is used a great deal, and

ing seen. furthermore, many systems of heating

Perhaps this crude example will exare very difficult to illustrate by any

plain why, in this perspective work, the other means.

circles on the fittings appear as ellipses. To get into this subject we show In making a rule for this work we can several simple examples of perspective in perhaps do no better than to say that the Fig. 150.

straight lines of pipe should be first put A represents a connection which in- in, in their proper directions, and the spection will show is viewed by looking fittings connecting them put in afterdown upon the object, and from the right, ward, and as previously stated, care be

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ing taken that the ellipses are square with the piping.

To make an application of the work shown in Fig. 150, we give Fig. 151, which represents a heater with its piping. It

the boiler. In perspective, all vertical lines appear vertical, hence all the risers in Fig. 151 are vertical.

The line of pipe S-T is at right angles to the boiler and therefore must be parallel with the front line of the boiler, that is, horizontal. The lines A-B and K-L are of course parallel with the lines V and W of the boiler, and must therefore be drawn in that way, that is, at 60 degrees with the horizontal.

The lines of pipe shown at C, D, M and N are parallel with S-T and E-F, and are therefore drawn horizontally with the tee square.

The lines of pipe shown by G, H, P and R being on the, work itself parallel to A-B and K-L are drawn parallel, that is, at 60 degrees with the horizontal.

In Fig. 151 we have lines of pipe running in four different directions in addition to the vertical lines, and we believe that this sketch will cover the ground

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Mechanical Drawing for Plumbers. Sketch Showing a Heater and its Piping.

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quite thoroughly, and therefore be of special value.

We might say that in perspective, the lines that run back, and away from the observer, appear to converge instead of appearing parallel, as they actually are.

This is illustrated by a straight line of railway tracks. We all know that if we look along a long stretch of track, the rails appear to converge, and if the distance is great enough, they seem finally to run together.

To be actually correct in showing the work of Fig. 151, the lines of pipe A-B and K-L, instead of being parallel; should be somewhat closer together from B to K than from A to L, but in mechanical perspective, as we may call the work that we are now considering, this principle is

not usually given any consideration.

Very often on such work as shown in Fig. 151 the work as far as we have carried it, is shown in perspective, while the radiators, and all other work above the connections in the cellar, the work would show plain, just as we have hitherto shown it.

In bringing this book to a close with the present chapter we would say that we have endeavored to eliminate as far as possible all technical matters connected with the subject, trying as far as possible to express and explain the ideas to be conveyed in as straightforward and plain wording as possible, for it has been our aim to make the book equally as valuable to the apprentice boy as to the well informed master.

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