148 Notice of the Discovery of the Termination of the 



11. Dr Goring's various improvements on the microscope, 

 as described in this Journal and elsewhere ; and his introduc- 

 tion of test objects. See this Journal, No. xx. Old Series, 

 p. 327, 360 ; No. ii. New Series, p. 64, 353 ; and No. viii. 

 p. 244. See also the Treatise on the Microscope published 

 by Dr Goring and Mr Pritchard. 



1 2. Mr Lister's discovery of the double aplanatic foci, and 

 variable aberration of achromatic object-glasses having their 

 inner curves in contact. 



In the preceding enumeration we do not pretend to give an 

 exact list of recent microscopical improvements : We have 

 merely mentioned those that happen to be best known to our- 

 selves. 



With regard to manual labour, we may give the following 

 enumeration : — 



1. The new and difficult art discovered by Mr Pritchard 

 of making diamond lenses. 



2. The great skill exhibited by Chevalier, Tulley, Amici, 

 Utzschneider, and others, in constructing minute achromatic 

 object-glasses. 



3. The art of giving the elliptical form to small specula 

 3-10ths of an inch focus, and of the same aperture, as perfected 

 by Mr Cuthbert. See this Number, p. 74, note. 



This enumeration of facts will, we hope, relieve the philo- 

 sophers and opticians of England and other countries, from 

 the charge of having given an unprofitable direction to their 

 intellectual and manual labours in the improvement of the mi- 

 croscope. That their inquiries have been pursued in the right 

 direction, may be safely inferred from the extraordinary success 

 with which they have been attended. 



Akt. XVII. — Notice of the Discover?/ of the Termination of 

 the Niger, in the Bight of Biafra. 



The discovery of the termination of the Niger has long been 

 a problem of some interest in geography. The direction of the 

 river seems to have been traced to a point in 10° of north lati- 

 tude, and 5° of west longitude, a little to the south of Yaory 

 or Youri, the place where Mungo Park appears to have been 





