IT. SELECTORS. 223 



883cc. Spottis wo ode's Pocket Polarising Apparatus, 



consisting of Nicol's prism, Savart's polariscope, tourmaline, 

 double-image prism, bi-quartz, dichroscope, and ^-undulation 

 plate. The Avhole is packed in a leather case, 2 inches long, by 

 | inch in diameter. W. Ladd fy Co. 



883d. Large Circle for measuring the Azimuths of Ellip- 

 tic and Rotatory Polarisation, and reproducing all experi- 

 ments of polarisation and reflection. 



School of Pharmacy, Paris. 



883d. Polariscope for detecting faint traces of 

 Polarisation independently of its direction. The wedges 

 are right and left-handed quartz, with their axes parallel to that 

 of the instrument. The eye should be placed in the focus of the 

 lens, with the Nicol interposed. Designed by the exhibitor and 

 made by Messrs. Tisley & Spiller. K. H. M. Bosanquet. 



883e. Arago's Polariscope. M. Lutz, Paris. 



883f. Savart's Polariscope. M. Lutz, Paris. 



883g. Tourmaline Plates. M. Lutz, Paris. 



883h. De Senarmont's Polariscope. M. Lutz, Paris. 



884. Wheatstone's Polar Clock. To determine the true 

 solar time by the polarisation of light reflected from the sky. 



The Council of King's College, London. 



885. Latest form of Wheatstone's Polar Clock. To 



determine the true solar time by the polarisation of light 

 reflected from the sky. 



The Council of King's College, London. 



Soleil's Compensator. S. Laurent, Paris. 



887. Norremberg's Polarising Apparatus, with Wheat- 

 stone's improvements. H. Lloyd, Trinity College, Dublin. 



888. Duboscq's Polariscope, for determining the incli- 

 nation of the axes in bi-axial crystals. 



//. Lloyd, Trinity College, Dublin. 



889. Wheatstone's Apparatus to illustrate the laws of 

 interference of polarised light. 



H. Lloyd, Trinity College, Dublin. 



