194 
Proceedings of the Royal Society 
hour; and a great increase will be remarked in the number of smaller 
and exceedingly minute stars. 
The 3rd represents, on the same scale though with a larger field, 
part of the Milky Way near that remarkable variable rj Argils. 
While the 4th shows the instrument with which the views were 
obtained. 
These photographs are evidently sharp enough to admit of being 
magnified several times linear, rendering the smaller stars more 
easily visible. Doubtless therefore, Dr Gill, who does everything 
well and on a continually rising ideal, will eventually have them 
magnified to that degree* or perhaps more ; and will make his 
Camera views of the stars, everything that such short focussed views 
can ever become. 
But I should warn the meeting that they never can rise up to 
the extraordinary importance of supplanting all the older forms of 
astronomy, as has been recently bruited about, with so much con 
fidence, by some very well-intentioned persons ; but who are not 
practically acquainted with either the excelsior requirements of 
intellectual astronomy on one side, or the limited capabilities of a 
photographic film, on the other. 
As the art-science now stands, and with the class of instrument 
used on this occasion, — exceedingly pretty, integrating views of 
what can be seen, on a very small scale, of the really unfathomable 
depths of the starry heavens, may be obtained, and will have their 
own particular uses and approximate applications. But any one of 
these mere Camera views is totally unable to differentiate to the 
terrible extent required by the higher astronomy of the present 
day. 
In double-star work for instance, and its most important attribute 
of being able to demonstrate a physical connection between one star 
and another, amenable to the calculations of Newtonian grav itational 
astronomy, — we ought to be enabled to divide a second of space 
into several parts with certainty. And for that purpose, such 
portion of space should be represented on a photograph by not less 
than f-Q of an inch. But that implies, in this case, a further magni- 
fying of not less than 70 times linear. Or the making, out of one 
of the photographs on the table, 4900 others, each as large as itself, 
