240 
James Small 
of the hole, and the instrument is raised by flat wooden blocks until 
the optical axis is on a level with the centre of the hole and with the 
glowing pinhead of the lamp. It is pushed as close up to the hole 
in the cardboard casing as the stand will allow. The section to be 
drawn is then inserted, and the chosen field illuminated as evenly 
as possible and as brightly as is compatible with clear definition of 
details. The Reflex Drawing Apparatus is now screwed on (the 
appearance of the field can be checked by turning the mirror upwards) 
and then the mirror is turned so that a bright, clear picture showing 
details and colouring as in the direct view is thrown upon paper 
placed flat upon the bench. 
The brightness of the image upon the paper varies, of course, 
with the amount of light from other sources. The stray beams from 
the hole in the cardboard casing have little effect, if the apparatus is 
properly fixed up. The image is faint in full daylight, but in twilight 
or when dark blinds of the now usual type are pulled over the windows 
the image is quite bright. Final adjustments of brightness can be 
made easily by using (i) a half cover of cardboard (Fig. 2) which shades 
the image from all extraneous light 1 except from the observer’s direc¬ 
tion and his shadow acts very efficiently from that side; (2) an ordinary 
night-light which can be moved about until lines drawn upon the 
paper are visible while the image still remains clear. Nothing more 
remains to be done now, except to draw lines in pencil or in ink 
around the outlines of cells and to fill in as many other details as are 
required in the same way; the actual process of drawing becomes 
easier and more rapid than tracing with transparent paper. 
The advantages of this method are—firstly, the ease with which 
the adjustments can be made when the apparatus has been in working 
order; secondly, the brightness and clearness and flatness of the 
image which make it possible to work in daytime without a dark¬ 
room; thirdly, the ease and comfort with which a camera lucida 
drawing can be made when one has the paper flat upon the bench 
and when both image and paper are viewed directly, and not one or 
other as a reflection; fourthly, the comparatively low price of the 
apparatus, especially when it is considered that apart from the reflex 
mirror the rest of the apparatus is useful for so many other illuminating 
purposes. The total cost is, in fact, less than that of many of the usual 
earnerce lucidce. 
1 These cardboard cases can be made easily by ruling heavily with a blunt 
point the lines for folding, and then fixing the edges which overlap with split- 
pin paper fasteners or drawing-pins. 
