TOTAX SOLAE ECLIPSE OE JULY 18, 1860. 
337 
The print exhibits the arrangement of the observatory, when secured after the day’s 
work. The position of the canvas, and the simple arrangement for maintaining it at 
the proper distance from the house, and also the outside cistern, are well shown in the 
picture, which is copied from a photograph taken on the occasion of Mr. Aiey’s visit to 
my station. When the observatory was at work, the canvas was removed from the front 
(the south side) and tied back as far as the upright which is seen on the western side, the 
top boards also being removed. The front boards were of a height which admitted of 
our observing the sun above them whenever it was desirable to do so. 
Photographic chemicals were prepared in duplicate ; part of the collodion intended 
to be used was mixed with the iodizing solution in London, and after subsidence was 
carefully decanted previous to packing, in order to avoid the defects before alluded to ; 
but coUodion and iodizing solution were also taken separately, so that some might be 
prepared on the spot, and used, if found free from defects, in that state of extreme sensi- 
tiveness which exists in collodion freshly iodized with the potassium iodizer. Nitrate- 
of-silver baths, prepared in the ordinary way with crystallized nitrate of silver, were 
taken, and were used in depicting the several phases of the eclipse, with the exception 
of those of totality. In taking the latter pictures the baths used were made with nitrate 
of silver which had been fused carefully in my own laboratory, and were so extremely 
sensitive that they would give photographs of the full moon in the focus of my reflector 
in less than a second of time, while with the usual bath five seconds were barely sufficient 
to give a picture of similar intensity. 
As few astronomers perhaps are aware of the number of materials required for such 
an expedition, I here give the list of contents of one of the boxes of chemicals. 
Packag( 
3S. Contents. 
Packagi 
Bs. . Contents.. 
3 
Half-pint bottles of Collodion. 
1 
5 OZ. Iodide of Potassium. 
1 
Four-ounce Bottle of Collodion, 
1 
Ounce Measure. 
iodized. 
1 
Gallon Distilled Water. 
1 
Half-ounce Bottle of Pyrogallic 
1 
Set of Scales and Weights. 
Acid. 
3 
Plate-drainers. 
1 
Six-ounce Bottle of Acetic Acid. 
1 
4 oz. of Tripoli. 
1 
1 5 -pound Bottle of Hyposulphite 
1 
Packet Cotton Wool. 
of Soda. 
1 
Glass Funnel. 
1 
Case containing Oxide of Silver and 
1 
Petort Stand. 
dilute Nitric Acid, in separate 
1 
Lantern. 
bottles, for correcting the bath, 
3 
Bottles of Varnish. 
in case of need. 
Test Papers. 
2 
24 oz. of Nitrate- 0 f-silver Bath. 
Filtering Paper. 
1 
2 oz. Crystals Nitrate of Silver. 
4 
8-oz. Mixing Glasses for Collodion. 
1 
4 oz. fused Nitrate of Silver. 
The apparatus, when completed, weighed 
34 cwt., 
, and was made up into thirty pack- 
