340 
ME. WAEEEN DE LA ETJE ON THE 
After having obtained the photographs and got them home safely, my work was only 
begun, I knew that they contained in themselves most valuable records ; but it did not, 
in the first instance, appear so clearly how I could turn them to account. The two 
totality pictures presented the most interest, and to them I first turned my attention ; and 
as it was evident that no measurements ought to be made on the originals, I then 
bethought me of the best means of multiplying them. In the first instance, I got some 
enlarged positive copies photographed by Mr. Downes, and, made some little progress in 
measuring them ; but I soon found that I should require others, and, on attempting to 
have some made a little later in the year, I experienced an amount of difficulty I never 
could have anticipated. The original negatives proved to be so extremely intense, that 
nothing short of unobscured sunlight would penetrate them and reveal their details ; so 
that it was only by working for many selected days with Mr, Downes, that I succeeded 
in getting a sufficient number of positive copies for my purpose. Those who remember 
how remarkably dull and wet the year 1860 was in England will readily understand 
that the selected days were few and far between, so that it was fast approaching winter 
before I had got on much with the work on the photographs. I also had recom’se to the 
albumen process, and obtained a few copies of the size of the original by superposition, 
without the intervention of the camera. These were made in my presence, at Messrs. 
Negeetti and Zambea’s, and from these positives some negatives were taken. Although 
these copies did not aid me greatly, it was fortunate they were taken ; for in course of 
time the original negative No. 26, the second of totality, gave indications of decay, and 
on attempting to save it by revarnishing it, the collodion expanded, and crinkled up so 
much that, except as a record of what was done, the original negative is spoiled. I have 
protected it from further injury by cementing it with Canada balsam to a second glass 
plate ; but one of the albumen negatives must now supplement it, if more copies are ever 
taken by direct superposition. Enlarged negatives, however, exist ; but, as something is 
always lost in copying, the damage to the original negative is unfortunate*. 
Measurements of the enlarged positives on glass of the totality pictures soon proved 
to me that the most accurate results could be obtained by measuring the photographs 
of the other phases, and that these results would indicate the path of the moon, and the 
position of the centres at the epoch of totality, independently of any determinations of 
geographical position. For this object it became necessary to measure the original 
negatives, because the slightest deviation of the optical axis of the copying camera 
from a right angle to the plane of the sensitive plate, or the least eccentricity, would 
cause a distortion of the cusps. I had, therefore, to devise an instrument for measuring 
the photographs ; and having considered how the object could be efiected, I put one in 
hand with Messrs. Teoughton and Simms, who constructed it for me with their usual 
skill and precision. After the instrument had been made, it was found to be conve- 
nient that some of the parts should be provided with a means of adjustment ; so that 
although it was commenced in February of 1861, it was not until July 18th that it was 
* The whole of the original negatives have been deposited with the Astronomer Eoyal. 
