123 



obtained the most distinct perception of the telescope's prodi- 

 gious bulk, which at a greater distance is not so striking, for 

 want of a standard of comparison ; yet, notwithstanding the 

 hugeness of the masses to be moved, so effective are all the 

 arrangements that Sir James South found it was possible to 

 uncover the mirrors and find a given star in less than eight 

 minutes. 



Unfortunately the whole month of February was of the 

 worst astronomical character ; and though the great speculum 

 had only the imperfect polish already noted, it was kept in the 

 tube as long as there were any hopes of seeing the great 

 nebula of Orion. That, however, was always clouded while 

 within its range. A few clear minutes on the 13th allowed 

 them to see some stars and clusters ; but the only circum- 

 stances worth mentioning were, that it shewed the stars of 

 Castor far apart without an eye-glass^* and that the stars of 

 the cluster 67 Messier, which Sir J. Herschel describes as 

 being from the eleventh to the twelfth magnitude, were many 

 of them as bright as those of the first appear in a three and 

 a-half feet achromatic. 



At length, when all hopes of Orion were lost in the twi- 

 light, the mirror was removed from the telescope, and polished 

 on March 3rd. Its frame is supported in the cubic chamber 

 of the tube by three strong screws which give the adjustment 

 of its optic axis. By unscrewing these, when the tube is ver- 

 tical, four wheels with which the frame is furnished come to 

 bear on a railroad fixed at the bottom of the chamber and 

 communicating over a bridge (laid from its door when neces- 

 sary) with another railway laid on an inclined plane of about 

 sixty feet. It is drawn up this by the declination windlass, 

 and at its top runs on a strong truck by means of which it is 

 drawn a quarter of a mile, on a common road, to the laboratory. 



The polishing machine differs in nothing but size from that 



* Only twenty-two inches of the mirror could act in this case. 



