CORRESPONDENCE. 
101 
A Useful Tool for Microscopists is thus described in the ' Ame- 
rican Journal of Microscopy ' for June. In setting needles in their 
handles, holding small tools for filing, grinding, &c., holding small 
pieces of hard material for filing or sawing, and a hundred other 
operations that every working microscopist requires to perform, 
nothing is so convenient as a good little hand-vice. The best article 
of this kind that has come to our notice is one made by the Miller's 
Falls Manufacturing Company. The jaws move parallel to each 
other, and are made of well-tempered steel. By means of a notch in 
the jaws, and a centre point in the main stem, it is easy to grasp any 
object so that it will be held true, and in this way the vice may bo 
used to hold drills, bits, &c. ; and by removing the wooden handle, it 
may itself be grasped in an ordinary brace. Descriptive circulars 
may be obtained from the manufacturers, at No. 74, Chambers Street, 
New York. 
COERESPONDENCE. 
Mr. Brown's Paper on Nobert's Lines. 
To the Editor of the ' Monthly Microscopical Journal.' 
Washington, D.C, June 29, 1876. 
Dear Sir, — The abstract of Mr. J. A. Brown's paper on the 
Nobert's lines, in the June number of your Journal, was the means of 
directing my attention to the original paper " On the Power of the 
Eye and the Microscope to see Parallel Lines."* It appears from 
the original paper, that the photographs so elaborately measured were 
a set of paper prints made at the Army Medical Museum, and sent 
thence to Mr. Eulenstein, of Dresden, in 1868. These photographs 
were the work of my former assistant. Dr. E. Curtis, who, through a 
misprint, figures in Mr. Brown's paper as " Dr. E. Carter, Surgeon of 
the U.S. Army." 
These photographs of Nobert's lines were described by me in a 
paper published in the ' Quarterly Microscopical Journal,' October, 
1868. I there expressly declared that the photographs of the 16th, 
17th, 18th, and 19th bands showed spurious lines only. All that 
Mr. Brown has so laboriously measured on these bands, as shown 
in the photographs, is therefore without any value as a measurement 
of the actual rulings of Nobert. I may say of his other measure- 
ments, that I can only regret that so much labour has been lavished 
upon paper prints, which are never of the same size as the original 
negatives, from which they always differ (after washing and mounting), 
both in magnifying power, in the thickness of lines shown, &c. To 
have any serious value as a study of the actual rulings, these measure- 
ments should have been made on the original negatives, or at least on 
glass contact prints. Should Mr. Brown be willing to undertake 
* ' Proceedings of the Koyal Society of London,' vol. xxiii. 1875, p. 522. 
