SECTION CUTTING. 



205 



graduation. This is screwed to a block of wood, r, having 

 a rabbet cut in for the purpose of securing it to the table. 



Fig. 13-2. Gibbon's Section Cutting Jfocfcfee. 



The machine is self-regulating, and is capable of being 

 worked as rapidly as the skill of the operator may dictate. 

 Sections of woods, when cut from hard woods containing 

 gum, resin, &c., should be soaked in essential oil, alcohol, 

 or ether, before they are mounted as transparent objects. 

 A razor may be fixed to the bench for the purpose of 

 cutting these fine sections, or a fine plane will answer very 

 well. The instrument used by Mr. Topping, fig. 133, con- 

 sists of a b, a flat piece of mahogany, seven inches long 

 and four wide, to the under surface of which is attached, 

 at right angles, a piece g of same size as a b. d is a flat 

 plate of brass, four inches long and three wide, screwed to 

 the upper surface of a b ; to the middle of this plate is 

 attached a tube of the same metal e i, three inches long 

 and half an inch in diameter, and provided at its lower 

 end with a screw f, working in a nut, and having a disk k 

 exactly adapted to the bore of the tube ; this disk is con- 

 nected with the upper end of the screw, and is moved up 

 or down by it c is another screw connected with a curved 

 piece of brass h, which is capable of being carried to the 

 opposite side of the tube by it. The piece of wood about 



