Royal Physical Society of Edinburgh. 3833 



Proceedings of the Royal Physical Society of Edinburgh. 



Saturday, January 8, 1853. — Prof. Fleming, D.D., in the chair. 



John Stewart, Esq., exhibited a collection of stereoscopic photographs, in illustra- 

 tion of which he made the following remarks : — 



For some time past, Mr. S. said, he had endeavoured to ascertain by experiment 

 the possibility of procuring a distinct representation of an object in motion, by means 

 of very sensitive photographic plates. He meant by this a correct likeness of an object 

 from an instantaneous exposure of a plate to its shadow while in motion. He was fully 

 aware that part of what he proposed was of old date, and that photographic plates had 

 years ago been rendered sensitive enough to require but an instant's exposure in order 

 to procure a picture. Talbot proved this when he caught the distinct image of a re- 

 volving wheel illuminated by a spark of electricity ; and an amateur photographer, 

 Professor Machonochie, told him, that while taking a view of the inauguration of the 

 Wellington statue in this city, he accidentally caught the distinct representation of a 

 flash of lightning that occurred, as many present will recollect, during the ceremony, 

 and which chanced at the instant he exposed his plate. He had not yet had the plea- 

 sure of seeing this photograph, but the Professor had kindly promised that he should 

 soon do so. However, in both these cases the rapidity of taking these views was 

 thrown from the operator on to the illuminating cause. Talbot's wheel was seen but 

 for a fraction of a second, and, if his plate was sufficiently sensitive, was sure to im- 

 press its outline thereon. So with his friend's flash of lightning, though there is a re- 

 markable difference in the two cases, the last being taken in the broad glare of daylight. 

 To obtain a view of a moving object in daylight, the case is different ; the rapidity of 

 action must then be thrown upon the operator, and the speed of the plate's exposure 

 must exceed the quickness of the object's motion, in order to ensure a distinct outline. 

 The summer before last he caught (for he could use no other word) distinct views of 

 many objects in motion, such as people walking, carriages moving, and the waves of 

 the sea. These were on single plates. What he wished to show the Society to-day 

 were stereoscopic views of the sea taken last summer. It will appear at once to every 

 one who understands the stereoscope, that two views are required for this object. These 

 two views must both be taken instantaneously from nature, and also at the same instant. 

 They must be taken instantaneously, to procure a distinct outline from nature, in order 

 that tbey may stand out in the instrument (which copies from a picture will not do), 

 and at the same instant, to ensure their uniting together. Those he had on the table 

 were so taken, and were views across Morecambe Bay, in North Lancashire. The 

 waves and ripple on the sea have a distinct outline, the hill of Blackcombe on the op- 

 posite side is fourteen miles distant, and light clouds may be distinguished hanging 

 half way across the bay. The process of preparing these plates Mr. Stewart at pre- 

 sent declined to communicate, as it was intimately connected with some researches he 

 was making to test the possibility of procuring natural colours along with a photogra- 

 phic view. He did not at present think it impossible that a process may be disco- 

 vered by which nature may be represented in her own colours by means of the oamera. 

 Some traces of colour he had already been able to procure, but as yet not the faintest 

 shade of that all-pervading one of green, which always comes out blaok in this style of 

 photograph. 



Hugh Miller, Esq., read a communication "On Bothrodendron, Ulodendron, Stig- 

 maria, and other characteristic Plants of the Carboniferous Period ; with a restoration 

 XI. Q 



