256 
THE SOLAR ECLIPSE OP 1898 . 
portance for this purpose. If a properly mounted telephoto lens be not 
available an excellent one could be improvised by placing a negative or 
concave spectacle lens behind an ordinary photographic lens. Such a 
spectacle lens can bo obtained from any optician for about a shilling, 
or the eye-glass of a short-sighted friend might be borrowed. The 
ingenious amateur would find no difficulty in constructing a simple 
camera in box form, and by varying the distance between the two 
lenses it is possible to get different degrees of magnification. It will, 
of course, not be possible to make an exposure longer than about 
1 second unless the camera be mounted so as to follow the sun’s motion, 
a condition somewhat difficult of fulfilment with a roughly constructed 
instrument. It would, however, be not at all impossible to improvise 
some arrangement by which the sun’s motion might be followed for a 
short time, say 5 seconds. If this could be accomplished good photo¬ 
graphs might undoubtedly be obtained. 
There are various ways in which this might be done. I shall here 
content myself with one or two suggestions, leaving the observer to 
develop the ideas in the direction his inventiveness leads him. 
The first requisite is that the camera should be mounted on an axis 
parallel to the axis of the earth. This presents no difficulties. To 
get the motion perhaps the simplest way would be to have a screw press¬ 
ing up against an arm attached to the camera. A small telescope with 
a cross-wire in the eye-piece must be fixed to the camera, and should be 
so adjusted that when the image of the sun is in the requisite position 
on the plate the cross-wire is tangential to the limb. The observer 
will then look through the telescope and move the instrument steadily 
by means of the screw, keeping the cross-wire always touching the 
limb during the time of exposure. This appears a laborious and diffi¬ 
cult process, but is perfectly feasible. One enthusiastic astronomer 
has proved that it is possible to take star photographs with an 
exposure of 1 hour , driving the camera by hand, so that an exposure 
of 5 or 10 seconds cannot be considered to present any insuperable 
difficulties. 
If an automatic movement be desired it might not be impracticable 
to design some form of water clock which would give a smooth and 
sufficiently regular motion. 
In conclusion, it may be pointed out that a total eclipse is one of the 
most impressive and fascinating of natural phenomena, and no one— 
whether he be astronomer, photographer, or mere spectator—should 
fail to take any chance of seeing one that comes in his way. The 
opportunities of seeing one are not many, owing to the very narrow 
band which constitutes an eclipse path on the earth. In India, in 
January next, a number of good stations are available and easily 
reached by railway. A map is here annexed, showing the path of the 
shadow, which has been reduced from the excellent map issued by the 
Indian Survey. The weather chances through Central India appear to 
be as good as possible, and we may therefore confidently look forward 
to successful observation and to a solid advance of knowledge. 
