in deep shadow by an exposure sufficiently long, but hitherto 
we have not been able to obtain these simultaneously. 
Several hundred views upon the table will show to what 
extent of perfection this principle of unequal exposure has 
been carried. 
As all of these views were obtained during last season, 
many of them at elevations of from eight to ten thousand feet 
above the sea ; and as the parts of the larger instruments had to 
be detached and carried separately and then mounted together 
on arrival at the elevated station, it may be safely alleged, we 
think, that the pantascopic camera is efficient in producing 
what it professes to do, and that it is a practical instrument 
bearing the necessary amount of rough usage inseparable from 
a campaign like that undertaken by the photographer who 
produced these views. 
Having already occupied so large a portion of your time, I 
will only add a few words as to the nature of the perspective 
in which these views are produced. 
It is a very common error to suppose that there is only one 
sort of perspective, and I was surprised to see that when the 
pantascopic camera was first explained to the Photographic 
Society of London, the vulgar view was entertained by at 
least two members of the council of that learned body. 
On that occasion, two gentlemen entered their protest 
against the assumption that the views shown or taken by the 
camera were true. 
The inventor very pertinently asked, What is truth — what 
is your standard ? Do you mean that the views are not in 
plane perspective? But I have already said they are 
panoramic views. How can they be in plane perspective if 
they are panoramas ? It was evident that to them there was 
but one perspective ; but it has been said by competent 
authority that there are as many kinds of perspective, as there 
are imaginable surfaces upon which to receive the visual rays 
passing from objects to the observer. At least three such 
