HENDRY, ON THE SACCHARO-POLARISCOPE. 249 



fixed below the stage. The tube thus prepared is to be 

 substituted for the body of the microscope, and retained 

 by one or more elastic bands c to the stand-frame, and 

 placed in a vertical position for use, resting close upon the 

 stage. 



Secondly, fit the top of the gutta-percha tube with 

 a turned wood stopple (not seen in the drawing), 1 inch in 

 depth, three fourths of which should enter the tube mode- 

 rately tight, just so as not to rotate, and one quarter should 

 constitute a collar or rest, say of 3 inches diameter, over- 

 hanging the tube, for convenience of handling on removal, 

 &c, and let this stopple be perforated in the direction of 

 its axis, with a T fi oth- or ^th-inch aperture ; then fix also 

 permanently upon its upper surface a compass card d, 

 marked in degrees of a circle, and with a corresponding per- 

 foration. 



Now prepare another stopple, e, of 1 inch in depth, and 

 lx inch broad at the bottom, tapering to l^th inch above, 

 and perforated as before ; let this be mounted upon the first 

 stopple, interposing the compass-card and a circular slip of 

 card or two to facilitate rotation, having a needle, r, inserted 

 laterally as an indicator to denote the arc of polarization. (The 

 two stopples may be turned out in one, and afterwards cut 

 across) . 



A piece of brass tubing, such as is used for jointing fishing- 

 rods, of about 2 inches in length, should be fitted firmly in 

 the perforation of the upper stopple, but made to rotate 

 freely within that of the larger or 

 under stopple, thus allowing the indi- 

 cator to be turned freely, and without 

 disturbance to the compass-card. The 

 analyser g, as usually employed above 

 the objective in ordinary polarization, is now placed within 

 the upper part of the brass tubing, projecting half an inch 

 above, and lightly packed with gutta percha, so as to have an 

 independent rotation, to adjust, fix, or remove at pleasure. 

 A slip of glass, h, of about 1 inch in length, may be inserted 

 in the body, having a gauge-mark drawn across it at a 

 distance of 7-^ 5 ths inches from the bottom of the tube (inner 

 surface), to ensure a given depth of the solution or syrup em- 

 ployed. The several parts being now duly centred, the appa- 

 ratus is complete for ordinary observation; but for com- 

 mercial or extended scientific research, a thermometer and 

 hydrometer will be required, with tables of reference. 



A syrup, prepared by boiling three or four ounces of loaf 

 sugar in a corresponding quantity of water and filtered, while 



