242 
The Philippine Journal of Science 
1918 
THE SQUARE-RULED MICROMETER USED AS A POSITION INDICATOR 
For the purpose of referring to specific parts of the micro- 
scope field in the discussion of objects in view under the com- 
pound microscope, the square-ruled ocular micrometer scale is 
in some ways superior to the field pointer. When so using the 
scale I assign numbers to the transverse rows of squares and 
letters to the vertical rows so that each small square in the 
scale may be specifically indicated by a number with a letter. 
The Zeiss scales that I use are not marked with numbers. If 
the scales were to be so marked I would prefer that the trans- 
verse rows be numbered and the vertical rows lettered. The 
obvious advantage of using this accessory instead of a field 
pointer is that many different parts of the field can be indicated 
without readjustment of the apparatus. 
THE SQUARE-RULED MICROMETER FOR DRAWING TO SCALE 
For use in drawing to scale from the compound microscope 
all students in my classes in botany and pharmacognosy since 
1911 have been supplied with square-ruled ocular micrometers. 
I have found it convenient to use for the drawing a thin 1 semi- 
transparent paper of suitable texture, and to place under it a 
paper scale ruled into squares corresponding to those of the 
ocular scale. Using a Zeiss No. 3 huygenian micrometer ocular 
containing a micrometer disk with a 5 mm square ruled at 0.5 
mm intervals each way and a paper scale 90 mm square ruled 
at 9 mm intervals, magnifications of 120 and 500 diameters 
are obtained with the Zeiss achromatic objectives A and D, 
respectively. As paper scales for any desired magnification 
can be easily provided, this method affords unrestricted choice 
within a greater range of available magnifications than can be 
had with a camera lucida. The dimming of the microscope 
image and the complication of light adjustments attendant on 
the use of the Abbe camera lucida are avoided by the use of 
the square micrometer as an aid in drawing. And the expense 
of equipment and deterioration is comparatively insignificant. 
CAPILLARY GLASS RODS FOR COVER-GLASS SUPPORTS 
In making Venetian-turpentine mounts of delicate objects as 
variable in size as the Volvocaceae it is desirable to have cover- 
glass supports of greater range of thickness than is afforded 
1 The use of a translucent drawing table illuminated from below, with 
the square-ruled scale on thin paper or on the glass of the table, would 
make it possible to use thicker drawing paper. 
