vi TABLE OF CONTENTS. 
PaGE 
V. Opreratine-Room anp Fixturms . . ..... . 56 
When a Heliostat isto be used . 2. 2. 1. . 56 
Heliostat Governor (Woodward’s) . . . . . . . 57 
Adjustment of the Heliostat . . . . . .. . . 57 
Window-Fixtures. . 2. 2... 1... wee BT 
Focusing Arrangement . . . : ee ee 
Camera suspended from above . . . .... . 59 
Photographing without a Heliostat. . . . . . . 60 
Inclined Position of the Apparatus. . jb) 36 60 
Exclusion of Extraneous Light . . . . . . . . 62 
Arrangement of Author’s Operating-Room . . . . 63 
VI. Prosection oF IMaGE, AND FocusING UPON THE SCREEN 65 
Removal of Eye-Piece. . 2. 6. ee 2 1 ee 65 
Focusing AerialImage. . . . . . . 1... . 66 
VII. Measuring UPON THE SCREEN. . ...... . 67 
Stage Micrometer. . . . . . . S ene, a OF 
Unit of Measurement . . . . . . .... . 67 
Method of Measurement . . ...... 2... 68 
VIII. DrapHracms In THE Puare-HotpmR. ..... . 70 
IX. Exposurror Puate . ...... bl a gl ck EE 
Time of Exposure, . . 2 2 4 8 @ « & « » « VI 
Drop-Screen . 72 
Actinic Power of Taeht Gutnes, iy Hazy ‘Ainge. 
phere, by Reflection, or by passing through Refract- 
ing Media. . . > Bie 322 
Angle of Aperture of Gites, ye ew ow 72 
Attenuation of Light by Divergence of — so AS 
Time of Ricgwenne with a Heliostat. . aoe we 4 18 
Without a Heliostat. 2. 2. 2... 1... 8 
With Lamplight. . . . .. « ae A 
Of Transparent Objects F BT 75 
Over-exposure. . . a Sy se . 76 
Under-exposure . . . . ere Eb bey 77 
X. DEvELOPMENTOF PhaTE. . . . . - . 78 
Ferrous-oxalate Developer . ee See Be ee, NS 
Developing Tray. 2 2. 2. 2. wwe 9 
Time of Development eos g . 80 
Image should be seen from Back of Plate. wea 80 
