18 



PRACTICAL TREATISE ON 



sented by figs. 14 and 15, and will be found to be accurately 

 described in a work entitled DUsertationes quatuor Johannis 



N. Lieberhihn, col- 

 lected and revised by 

 John Sheldon, sur- 

 geon, 1782. It con- 

 sists of a plate of 

 copper or brass, about 

 one-eighth of an inch 

 thick, twelve inches 

 long by eight broad, 

 and fashioned into the 

 shape represented by 

 the figures. It is sup- 

 ported, in a vertical 

 position, on a tripod 

 stand, the back of the 

 instrument is repre- 

 sented by fig. 14, and 

 the front by 15. At 

 each corner there is 

 a small sliding wire, 

 H H, with a hook at 

 one end, and opposite 

 to the three holes in the plate marked A B and C are 

 four smaller hooks, h h, the former are for the purpose of 

 fixing into the legs of any small animal, the circulation in 

 whose mesentery, either of the blood or of the chyle, is 

 about to be examined; and the latter, or the small hooks, 

 are used for bringing successive portions of the mesentery 

 opposite the holes. 



The part of the microscope carrying the magnifying powers 

 is attached to the plate by pegs ; it consists of a thin plate of 

 brass, 1, fig. 15, to which plate is attached another, 2, by a 

 rivet, 3, this last plate is a little curved, and is also made 

 elastic; in its centre is a screw, 4, and at its free end is 

 a hole, 5, into which the magnifier screws; a section of 

 this part of the microscope is seen in fig. 16, where A re- 



Fig. 14. 



