1895.] MICROSCOPICAL JOURNAL. 163 



taken that the rotation by means of the connecting rod 

 shall occur without dead-space or backlash. Prof. Klein 

 states that some important details in connection with 

 improvements in the mode of carrying out this simulta- 

 neous movement of polarizer and analyser will shortly be 

 published by Herr Friess. Provision has likewise been 

 made for correcting at any time the setting of the nicols 

 in their carriers, experience having shown that the set- 

 ting invariably alters slightly in course of time. In ad- 

 dition to the eye-piece nicol capable of being connected 

 with the polarizer in the manner just described, there is 

 likewise provided the usual nicol capable of sliding in or 

 outof the microscope tube just over the objective. Above 

 this, and just below the eye-piece, a Bertrand lens for 

 observing interference figures in convergent light is ca- 

 pable of sliding in and out of the tube, and is intended 

 to be employed in conjunction with a converging system 

 of lenses capable of being carried in a tube attachment 

 beneath the level of the stage. The remaining details of 

 the microscope are the same as are usually supplied with 

 a No. 1, Friess instrument. 



The stage goniometer is intended to be employed 

 with the microscope arranged horizontally, as it is found 

 inconvenient to employ our immersion liquid with a ver- 

 tical arrangement. The base-plate of the goniometer, 

 consisting of a stout metal plate with fairly large cen- 

 tral aperture, is fixed by a suitable clamping arrange- 

 ment upon the new vertical stage of the microscope. 

 The plate is continued into a short arm on that side 

 which is uppermost when fixed in position, and this arm 

 carries near its end, and at right angles to it (horizontal 

 when in position), a projecting piece terminating in the 

 supporting cone for the goniometer circle, and which 

 also carries the vernier reading to five minutes and the 

 fine adjustment. The circle is hollowed in its upper cen- 



