712 SUMMAKY OF CUERENT RESEARCHES RELATINa TO 



large tube, but do not regard tlie difference as sufficiently important 

 to justify the naming of still another size. There remains, however, 

 a very large variety of medium-sized stands, a class believed to be 

 rapidly increasing in numbers and importance, which cannot, without 

 a total change of character, be raised to 1 • 35, and which should not, 

 in our opinion, be reduced even to 1. We therefore propose a stan- 

 dard medium size, 1 • 25, which we believe well adapted to a great 

 majority of pui'poses, with the alternatives of 1 and 1 • 35 for those 

 who wish smaller or larger tubes. Suitable adapters would harmonize 

 apparatus previously made with these sizes, and these sizes with each 

 other. We would also suggest the great convenience of uniform dia- 

 meter in the upper tube of the ocular for the easy interchange of 

 camera-lucidas, analyzers, &c. There seems to be no serious disad- 

 vantage in having this tube of uniform diameter in stands of various 

 styles and sizes; and we would recommend that 0*75 in., or some 

 smaller size, be made a standard. We would also recommend that the 

 diameter 1 • 50, recommended by the Eoyal Microscopical Society for 

 substage tubes, is in very general use and well adaj)ted to both large 

 aud reasonably small stands, and we recommend its adoption to this 

 Society. 



3. The following resolutions are therefore submitted to the con- 

 sideration of the Society : — 



Eesolved, That this Society recommends that oculars be named 

 by their equivalent focal distances on the basis of 1 in. focus cor- 

 responding to 10 diameters of amplification at 10 in. distance, 

 and that this nomenclature be employed in the Proceedings of this 

 Society. 



Eesolved, That this Society recommends the adoption of the dia- 

 meter 1 • 25 in. outside measure as a standard size of ocular tubes, 

 with a preference for 1 and 1*35 where smaller or larger sizes are 

 required, and recommend • 75 outside measure for ocular cap tubes, 

 and 1 • 50 in. measui'e for substage tubes. — E. H. Ward ; A. L. Smith ; 

 J. D. Hyatt ; George E. Blackham." 



Mr. W. H. Bulloch objected to the report on the ground that the 

 committee appeared to have followed the English system, which has 

 1 • 35 for the largest piece. The system is not well adapted for America, 

 he said, because there are no instruments there that are made according 

 to the English system. No changes in the parts of an instrument can 

 be made. The amplifying power of the eye-piece ought to be the 

 basis of the standard, and not the focal size. There is no make of 

 instruments that correspond to the standard the committee recom- 

 mends. He also spoke of variations that the density of the glass will 

 cause in the magnifying powders of eye-pieces that are made according 

 to the same formula. 



Dr. G. E. Blackham thought the report should be postponed till 

 next year. 



Mr. J. D. Cox thought it questionable if the standards should be 

 so confined as the report recommended, " because different gi-ades are 

 required even by the profession." 



The Society in the result ordered the report to be published in the 



