226 MEMORANDA. 
slide was to be placed next the stop (that is, on the left hand). 
Smith, Gregory, and perhaps all others previous to the finder 
coming into use, placed the label on the right hand of the 
observer, the label or top of the letters on the label indicating 
the top of the slide, the other end being the bottom ; but from 
supposing that the arrow-head on the finders sold imdicated 
the top, and not the bottom (as I am informed by Mr. Cop- 
pock, of Smith and Beck’s firm, was intended), many have 
got into the practice of placing the label or top of the 
slide also next the stop (on the left). The microscopists of 
Edinburgh, Hull, and some of those in London, place the 
label next the stop; those of Glasgow, Liverpool, and most 
(as I understand) of those in London, retain the method 
of Smith and Gregory, and place the label or top of the 
slide on the right hand. Uniformity in this respect, to 
enable one to consult a slide marked by another, is very 
desirable, if not absolutely necessary. 
But supposing that this point was settled, another differ- 
ence arises in the notation. One method is to consider the 
lines bounding the cell or square as similar to those of longi- 
tude and latitude drawn on a map. The interior of the square 
occupied by the numbers may be subdivided into sixteen parts 
by four imaginary vertical and horizontal lines. Thus, if the 
square was oe: an object on the vertical boundary of the 
square on the left hand would be registered as 20 exactly, or 
if on the right hand by 21; and the longitude between these 
would be 20°25, 20°5, or 20°75, according to its place within the 
square. Thus, also, the upper edge or line of the square would 
be called 30, the lower limit 31, and the latitude between these 
registered as 30°25, 30°5, or 30°75. An object a little—say one 
fourth—below the top line, and about three fourths from the 
20°75 
30°25 
5 
very centre of the square by Ss the line separating these 
left-hand boundary, would be registered by ? or if in the 
numbers (as in vulgar fractions) being merely to connect them 
together. 
All the other methods (and, if I rightly understand Mr. 
Maltwood’s observations, this was his intention) view the 
figures as indicating the square itself, not its limiting lines, so 
that an object found within the walls of the above square would 
be marked Ay But here there are two modifications in use. 
—One is to view a line (as in fractions) drawn to separate the 
