ii8 



KNOWLEDGE & SCIENTIFIC NEWS. 



[June, 1905. 



vertical plane. This is accomplished by makings a 

 small wooden frame, on the insidcs of which grooves 

 are cut for the insertion of the efratingf. At the bacic 



Such an adapter as above described is shown in the 

 accompanying; illustration. (Fig. 2). This shows ,i 

 gfrating attached to a 5 by 4 Kodak, and experience 



Plgr. a.— The K"*.\a% attached to a 5 by 4 Kodak Ca 



of this frame a circular adapter is fixed so that the 

 frame can be placed tightly on to the hood of the lens. 

 It is advisable to make the frame and circular adapter 



Fljf. 3. -A rough home* made Camt-r 



ilh KratinK attached. 



as close fitting as possible, and Id pia. e the grating- 

 side of the g^lass towards the lens, because the front 

 lens should be as near to the grating as possible. .A 

 great advantage of the latter instruction is that the 

 grating surface is protected from damage. 



has pro\ cd tiiat the arrangement serves all practical 

 purposes. 



Those who possess more lenses than cameras can 

 easily make a box-form of camera, the focussing being 

 done either by moving' the lens or by mounting the 

 dark slide in a framework which moves in and out of 

 the box. The accompanying figure (Fig. 3) illustrates 

 a home-made camera, which has already done yeoman 

 service on many occasions. 



A camera fitted with a grating- in the way above 

 described when lurncd directiv towards the sun shows 



an image of the sun in the centre of the ground glass, 

 and a spectrum on each side of this image; these arc 

 the first order spectra given by the grating-. l'"urther 

 away from the direct image still, and again on each 

 side of it, will be found another spectrum, fainter, but 



