NOTES AND CORRESPONDENCE. 
Maltwood’s Finder,—Although I prefer, when only four or 
five different kinds of objects are to be noticed in a slide, to 
mark them with pen and ink, placing (apparently) over each 
one dot to the form which is most frequent, and a short 
straight line or a semicircle also above the object when less 
frequent, or a triangle or circle of dots or a circle around the 
object when still more scarce, there can be no doubt that the 
finder proposed by Mr. Maltwood is superior to all others 
when it is thought objectionable to disfigure the cover with 
ink, or when the ink is hable to be rubbed off, which it is 
when not mixed with a little sugar or isinglass. My present 
object is to call attention to the various modes of using the 
finder, so that at present, when one receives a slide from a 
correspondent, his system of notation must first be ascer- 
tained, and then each object noted on the label have its 
marks changed to make them uniform with the other 
slides in the receiver’s cabinet, thus rendering new labels 
necessary. 
But first let me notice that, although I have three of these 
finders, one from Smith and Beck, another from a different 
London optician, of whose name I am uncertain, and the 
third from Bryson, of Edinburgh, none of these correspond 
with the directions given by Mr. Maltwood in the ‘ Micro. 
Journ.,’ VI (Trans.), p. 60, last line, and p. 61, line 5. It is 
there proposed that the figures representing the latitude 
should be written in the upper part of each square, and those 
of the longitude in the lower part. In all the finders I have 
seen this is reversed, the wpper row representing the longitude 
(east longitude of maps), and the lower the latitude (south). 
This has to be kept in view in the following observations. 
The first and greatest difference in the notation arises 
from Mr. Maltwood not having specified which end of the 
