373 



be taken up again. Ruling up to a fineness of 90,000 to the inch 

 had been quite successful, but those at 100,000 and 120,000 had 

 been less so, partly owing to the diamond and partly to the glass- 

 Mr. Grayson was now trying to find a splinter of diamond which 

 would rule these finer markings perfectly, as the machine itself 

 was quite equal to doing it. The great distinctness with which 

 the lines Avere seen was due to the manner in which they were 

 mounted. The earlier specimens were mounted dry ; but as this 

 was not satisfactory, Mr. Grayson had sought for some medium 

 which would render them more distinct and permanent, and he 

 had now mounted them in a realgar having a refractive index of 

 2 '5, and though this had a tendency to crack after about three 

 years, it was the best that had yet been found. The result was 

 described by Mr. Nelson as being the most perfect of the kind 

 which had yet been produced. If the diflSculty as to the diamond 

 could be overcome, he hoped to be able to send over some much 

 finer examples than those now shown. 



The Chairman said that those who had the opportunity of 

 seeing these rulings would agree as to the wonderful precision 

 with which they had been produced. It was said that seeing 

 was believing, but in this case they must hear also before they 

 could believe what they saw, for without the explanation given 

 no one would believe it possible to rule lines so numerous in so 

 small a fraction of an inch. Their thanks were due to Mr. 

 Wedeles, not only for bringing these slides for them to see, and for 

 what he had told them, but also for promising to send them some 

 further examples later on. He hoped he would let Mr. Grayson 

 know how greatly his work had been appreciated. 



In reply to Mr. Karop, Mr. Wedeles further mentioned that 

 the diamond points were obtained by breaking a diamond with a 

 hammer : also that the lines w^ere not filled in with plumbago or 

 other substance, but that their blackness was due to the high 

 refractive index of the realgar. 



Mr. Earland read a paper on " Cyinhaloj)ora hulloides d'Orbigny," 

 one of the Foraminifera. The paper was illustrated by diagrams 

 and specimens. 



The President, in inviting remarks upon the subject of the 

 paper, regretted that he could no*y himself discuss it, as he was 

 only one of those who were walking round the outside of the 

 subject ; but they were interested in what they heard and saw, 



