1994 Journal of Applied Microscopy 



of the wood by means of the brackets usually sold for the purpose. On 

 these rods are placed a number of " lion-jawed " hooks, which can be purchased 



at any bookstore, attached to a short length of brass 

 tubing a little larger than the rods. This tubing is 

 soldered securely to the hook. (See Fig. 2.) 

 Mounted in this way the hooks can be easily 

 slipped along the rod to the proper place, but when 

 released by the hand become clamped, due to the 

 weight of the chart, and thus keep the charts in 

 place and " taut." (Fig. 1.) With this arrangement 

 ^ .^ it is possible to keep long muslin charts tight and 



smooth, something difficult to accomplish except 

 where charts are mounted on wooden rollers. 



This rack possesses the following good points : 



1. It can be made of any size or shape. 



2. Materials of construction are all commercial articles. 



3. Any sized charts can be used and quickly hung. Charts of different 

 kinds of material and binding can be used at the same time. 



4. Muslin charts can be kept " taut." 



5. All charts are easily hung and taken down. 



University of Wisconsin. W. D. FrOST. 



An Attachment to the Minot Microtome for Cutting Sections 

 of One Micron Thickness. 



In 1896 the author designed and constructed a microtome after the Minot 

 pattern with an attachment for cutting sections from 1 to 25 micra thick. It 

 has been used for six years, and has proved so satisfactory that I venture to 

 describe it somewhat in detail. Accuracy, simplicity, and compactness are very 

 essential attributes in any piece of apparatus. 



The attachment occupies no more space, and is but little more complicated 

 than the old style Minot. It consists of two rachet wheels (Fig. 1, A and B) 

 with cog gear wheels attached and so arranged that they may be readily thrown 

 into or out of play. The notches on ratchet wheel A are so cut that each is 

 equal to .005 mm., or 5 /<. Those on ratchet wheel B are equal to 1 yu. The 

 gear wheels C and A are so cut that five notches of B are equal to one of ratchet 

 wheel A. The notches of B are shorter than those of A. It is therefore easy 

 to calculate the distance out on the lever K that the dogs F and E should be 

 placed so that each would move over the same number of notches on their re- 

 spective ratchet wheels. The wheel J is arranged so that the different positions 

 give from one to five clicks on either wheel. The spring I extending between 

 E and F is sufficient for both dogs. 



If one desires to cut sections from 1 to 4 micra thick, E is held out of play 

 by the prop G. Then the dog F will move ratchet wheel B the number of 



