2i8 Forestry Quarterly. 



sheets by closing the dry sheets in a water-proof paper envelope. 

 Wet map sheets are slipped into the drawer. 



The materials cannot warp. The two thicknesses of veneer are 

 added to give stiffness to the lower aluminum plate to which is 

 attached a brass plate holding the staff head. These veneers 

 are glued with water-proof cement and the grain of each piece is 

 at right angles to the grain of the other. The warping tendency 

 of one would counteract the warping tendency of the other. 



The aluminum and brass metal parts are designed both for 

 strength and lightness. The thickness of the aluminum plate, 

 .065 of an inch, is sufficient to give all the stiffness desired for the 

 upper plate. The lower plate having the greatest strain is rein- 

 forced by the veneers. 



The aluminum plates are of dull finish metal. This frosted 

 surface will not reflect bright sunlight and the surface is durable. 

 A varnish would wear off. No iron or steel has entered into the 

 construction of the sketching case. 



This instrument has been designed to meet both the require- 

 ments of Jacob staff-plane table and a map sheet holder. It is 

 equipped with straps, so that it can easily be held in the hand. 

 In addition, a brass plate is fitted to adopt the staff mountings of 

 the Gurley Forest Service Standard Compass No. 335. This 

 brass plate is thin and not in the way when the case is held in the 

 hand. When desired the case can be mounted as a plane table by 

 simply screwing the Jacob staff mountings of the Forest Service 

 Standard Compass into the brass plate for the purpose. 



A water-proof case can be made for the plane table-sketching 

 case to protect the instrument from wear when it is not in use. 



The advantages of this design over previous designs lie in the 

 provisions for safe-guarding finished and unfinished sheets, its 

 lightness and adaptability for a two-fold purpose- 



The plans have been sent to a reliable firm, which estimates the 

 cost of constructing a sample board at not more than $25. 



