98. The measure point for any system of horizontal lines will be found on VH as far from the vanishing point of the system as the horizontal projection of that vanishing point is distant from the horizontal projection of the station point.

Note. - In accordance with the construction shown in Fig. 26, SPV will always lie between the vanishing point of a system and its measure point.

99. The measure point of any system of lines is usually denoted by a small letter m with an index corresponding to its related vanishing point. Thus, mab signifies the measure point for the system of lines vanishing at vab.

100. The vanishing point for ah in Fig. 26 has been found at Vab. The point n, in HPP, is the horizontal projection of this vanishing point. The measure point (mab) for all lines vanishing at Vab will be found on VH, at a distance from Vab equal to the distance from n to SPH (98). In accordance with this statement, mab has been found by drawing an arc with n as center, and with a radius equal to the distance from n to SPh, and dropping from the intersection of this arc with HPP a vertical line. mab is found at the intersection of this vertical line with VH.

SIDE ELEVATION OF HOUSE FOR MRS. C. BIRTON ELLIS, SENECA LAKE, N. Y.

A. Raymond Ellis, Architect, Hartford, Conn. For Perspective View and Second-Floor Plan, See Page 122. Garden Elevation Shown on Opposite Page.

GARDEN ELEVATION OF HOUSE FOR MRS. C. BIRTON ELLIS, SENECA LAKE, N. Y.

A. Raymond Ellis, Architect, Hartford, Conn. Side Elevation Shown on Opposite Page. For Perspective View and Second-Floor Plan, See Page 122.

101. The perspective of ab has been drawn from ap, vanishing at vab. apbl on VH1 is made equal to the length of ahbH given in the plan of the card. A measure line through bl, vanishing at mab, will determine the length of apbp. A line from bp vanishing at vad, and one from dp vanishing at vab, will intersect at cp, completing the perspective plan of the card.

102. Even the vanishing points (vab and vad) for the sides of the card may be found without drawing a diagram. Since fn is drawn parallel to ab, it makes the same angle with HPP that ab makes. Similarly, since fh is drawn parallel to ad, it makes the same angle with HPP that ad makes. The angle between fn and fh must show the true angle made by the two lines ab and ad in the diagram. Therefore, having assumed SPH, we have simply to draw two lines through SPH, making with HPP the respective angles that the two sides of the cards are to make with the picture plane, care being taken that the angle these two lines make with one another shall equal the angle shown between the two sides of the card in the given plan. Thus, in Fig. 27, the two projections of the station point have first been assumed. Then through SPH, two lines (fn and fh) have been drawn, making respectively, with HPP, the angles (H° and N°) which it is desired the sides of the card shall make with the picture plane, care being taken to make the angle between fn and fh equal to a right angle, since the card shown in the given plan is rectangular.

Verticals dropped to VH from the points n and h will determine vab and vad. Having found vab and vad, mab and mad should next be determined, as explained in § 98. VH1 should now be assumed, and ap chosen at any point on this line. It is well not to assume ap very far to the right or left of an imaginary vertical line through SPV.

From ap the sides of the card will vanish at vab and vad respectively. Measure off from ap on VH1, to the right, a distance (a pb1) equal to the length of the side aHbH shown in the given plan. A measure line through b1, vanishing at mab, will determine the length of apbp. Measure off from ap on VH1, to the Left, a distance (apd1) equal to the length of the side aHdH shown in the given plan. A measure line through d1 vanishing at mad, will determine the length of apdp.

From bP and dp the remaining sides of the card vanish to vad and vab respectively, determining by their intersection the point cp.

The line ahdh in plan is divided by points th, sH, and rH. To divide the perspective {apdp) of this line in a similar manner, lay off on VHt from ap, to the left, the divisions t1, s1 and r1 as taken from the given plan. Measure lines through t1, s1, and r1 vanishing at mad, will intersect apdp, and determine tp, sp, and rp.

103. As has already been stated, the true length of any line is always measured on VH1, and from the true length, the length of the perspective projection of the line is determined by measure lines vanishing at the measure point for the line whose perspective is being determined. Care must be taken to measure off the true length of the line in the proper direction. The general rule for doing this is as follows : -

If the measure point of any line is at the right of SPV, the true length of the line will be laid off on VH1 in such a man= ner that measurements for the more distant points in the line will be to the left of the measurements for the nearer points.

Thus, mad is at the right of SPV. The point dp is more distant than the point tp. Therefore, the measurement (d1) for the point dp will be to the left of the measurement for the point tp. In other words, since mad is to the right of SPV, d1 which represents a point more distant than t1, must be to the left of t1 the distance between t1 and d1 being equal to the true length of tpdp, as shown by t hdh in the given plan.

On the other hand, if the measure point for any system of lines is to the left of SPV, the true measurements for any line of the system should be laid off on VH1 in such a manner that measurements for more distant points on the line are to the right of measurements for the nearer points of the line.