Answers to Queries. 217 
409.—Another Rule Wanted.—I do not profess to be a mathe- 
matician ; at the same time, I cannot help thinking that your 
correspondents have gone a long way round to answer a very 
simple question. ‘The following appears to be a common-sense 
view of the case, although it may be somewhat “wordy”; but I 
suppose those who answered this problem used an argument 
perhaps quite as lengthy as mine if they have not shown it. The 
rod is divided thus :— 
3 
WW 
28 fh: | i 
A 
Eeuisezo Teck. 
BC is 4 of B E, and is consequently = of C E. 
1l 
€- Dis + of C E, and is consequently = OLD SE 
. . oo, th . 
AD is= of entire length ; therefore, D E is ~ of entire length, 
1 4,\' 5244 #424356. 56 3 SGN) |) DOr 2 Ue ia 
Tag Ot 7) = 91 Se of @) = Siar esis 
7 14 . 4 : , 
I—g, 5) Showing that | are required to make the rod complete, 
and as we know that a is 28 feet, we say, 14:28 :: 91: 182 feet 
the answer. PUZZLED. 
= 
7 
415.—Drawing Micro Objects. I use a Beale’s neutral-tint 
reflector for drawing objects, and find it simple and easy to work 
with after I acquired a little skill by practice. There is no royal 
road to drawing micro objects for any amateur. Just study the 
directions given so fully in any of the numerous books on using 
the microscope, and regulate the light carefully. I make the 
outline only with the neutral-tint reflector, and fill up the details 
from direct observation. There is a difficulty to be overcome 
here, because the object or its image is “doubly reversed,” if I 
may use the expression, by the reflector, and one has to become 
accustomed to the change before being able to work in the parti- 
culars. The “ best and cheapest instrument” for any purpose is 
that one which does its work well and is not too costly. Such are 
any of the ‘‘cameras ” manufactured for fitting on to the eyepiece 
of the microscope. I have read in Science Gossip, Vol. XXIL., 
p. 172, that it is possible to make an efficient article with a small 
pill-box and a cover-glass, which would surely be the ‘“ cheapest ” 
instrument; but I never saw one except in the drawing illustrating 
that article. Ei. W.. Lett, M.A. 
