My latest Grubb lens is an Aplanatic 12x10 No 5350, made by Howard Grubb in aluminium, and dating, I believe, from the 1890s. It has a diaphragm aperture control with the RPS scale f11.3 which was introduced between 1895 and 1902. The other f stops are f16,22,32, 45 and 64. The lens element is orange coated which may indicate astronomical, scientific, industrial or military use. Someone has suggested that it might have been for meteorological purposes as the orange filter would enhance the contrast in cloud formations. Suggestions about possible uses would be most welcome.

Click image for larger version. 

Name:	IMG_2049.jpg 
Views:	11 
Size:	41.7 KB 
ID:	222153

Click image for larger version. 

Name:	IMG_2051.jpg 
Views:	10 
Size:	45.9 KB 
ID:	222154

Click image for larger version. 

Name:	IMG_2052.jpg 
Views:	10 
Size:	41.9 KB 
ID:	222155

Click image for larger version. 

Name:	IMG_2054.jpg 
Views:	10 
Size:	28.7 KB 
ID:	222156

Comments welcome.

William