SUMMARY OF CURRENT RESEARCHES RELATING TO 
534 
(4) Photomicrography. 
New Heliostat.* — Dr. Lyman S. Deck writes as follows: — “This 
simple and inexpensive form of heliostat, some idea of which can be 
gained from the accompanying illustration, is designed more especially 
Fig. 73. 
A, Triangular frame on levelling screws B. D, Plate of clock movement. 
C, Brace for inclining movement at proper angle. E, Posts on which clock-plate 
turns. F, Mirror frame on joint Gr. H, Hour spindle carrying wheel with 10 cogs. 
I, Wheel for reversing the motion of the mirror. J, Wheel having 40 cogs on 
spindle carrying the mirror. K, Brass case to protect the clockwork from dust. 
for use in photomicrography and with projection apparatus. It is con- 
structed on a principle similar to the equatorial telescope, and consists 
essentially of a mirror revolving on an axis parallel to the axis of the 
Proc. Amer. Soo. Mier., xiii. (1892) pp. 49 and 50. 
