OF MICROSCOPIC OBJECTS. 101 



ture. There is no monotony in this study, as the forms are so 

 various, and the arrangement of the cells and woody fibre so dif- 

 ferent, that the microscopist may find endless amusement or study 

 in it. From a single section the class of trees to which it has be- 

 longed may be known, often even when the wood is fossil. The 

 apparatus best adapted for cutting these sections is made as fol- 

 lows : A flat piece of hard wood, about six inches long, four 

 wide, and one thick, is chosen, to which another of the same size 

 is firmly fixed, as as to form in a side view, the letter T. On 

 one end of the upper surface is fastened a brass plate, perfectly 

 flat, in the centre of which a circular opening is cut about half an 

 inch in diameter. Coinciding with this opening is a brass tube, 

 fixed in the under side of the table (if it may be termed so). This 

 tube is so cut at the bottom as to take a fine screw. Another 

 screw is also placed at the same end of the " table," which works 

 at right angles to this, so that any substance in the tube may be 

 wedged firmly by working this last screw. To use this instru- 

 ment, the piece of wood or other object of which a section is re- 

 quired must be placed in the tube, when, by turning the screw 

 underneath, the wood is raised above the brass plate more or less 

 as wished, and by using the screw at the end, it is held firmly in 

 the same position. With a flat chisel the portion of the object 

 which projects above the surface of the brass plate may now be 

 cut off, and by means of the bottom screw another portion may 

 be raised and treated in the same manner. As to the thickness 

 of which objects should be cut, no proper directions can be given, 

 as this differs so greatly that nothing but experience can be any 

 guide. The same thickness can be obtained by working the screw 

 underneath in uniform degrees, the head being marked for this 

 purpose ; and when the substance to be cut is very much smaller 

 than the hole in the brass plate, it may be wedged with cork. 



As this instrument is peculiarly adapted for cutting wood 

 (though used for other substances, as before mentioned), I shall 

 notice a few particulars concerning this branch of sections. It 

 may here be remarked, that to obtain anything like a true know- 

 ledge of the nature of wood, it should be cut and examined in at 

 least two directions, across and along. The piece of wood is often 

 placed in spirits for a day or two, so that all resinous matter may 



