Large Nicol Prisms

Abstract

IN the account of Dr. Spottiswoode's physical apparatus, lately given to the Royal Institution, there are allusions to several large Nicol prisms said to have been made by Mr. Ladd and by Messrs. Sisley and Spiller. Although it is no doubt the trade custom to mention only the names of opticians who sell pieces of apparatus, and not of any of those whom they employ to make them, I still venture to hope that in this case, where skill and labour of a very special kind were required, the name of the actual maker of the above-mentioned prisms may not be forgotten. I would therefore respectfully ask permission to give a few particulars as to size, &c., of some of the larger Nicol prisms which I have myself made from blocks of Iceland spar within the last thirty years.