46 REPORT — 1891. 



Many members of the Mancliester Geographical Society had been taking 

 photographs, and in time a large number of negatives would be collected, 

 which the owners would, no doubt, be willing to place at the disposal of 

 the Committee if it were known that they would be safely deposited in 

 some accessible place, and a record giving the source and locality of each 

 negative also kept. 



Mr. Jeffs stated in reply that a list of the views which had been 

 received would be kept, and also a register for entering the name of the 

 person responsible for borrowing a negative. He suggested that the 

 Committee might make arrangements with some photographer for pre- 

 paring lantern slides from the photographs at a fixed charge, for the 

 purpose of lecture illustration. With respect to the photographs taken 

 by the members of the Manchester Geographical Society, Mr. Jeffs said 

 that their Committee would be very pleased to receive them whenever 

 they were sent. 



Mr. William Gray stated that he was interested in the subject of 

 geological photography in the North of Ireland, and he approved of the 

 scheme put forward by the Committee, of which Mr. Jeffs was the Secre- 

 tary. He had succeeded in securing a few photographs, which were 

 sufficient to show the value of the method both as applied to this subject 

 and to the erosion of the sea-coast. He expressed the opinion that it 

 would be an advantage if each Delegate were appointed as the local repre- 

 sentative of the Committee in his own district, and authorised to collect 

 the photographs. There were many members of his society (Belfast 

 Naturalists' Field Club) who had done a great deal of photographic work, 

 but there was some amount of hesitation in forwarding negatives to the 

 British Association Committee, which he thought would be got over if there 

 were some person in the society directly authorised to collect the photo- 

 graphs. Mr. Gray expressed his willingness to act in this capacity for 

 the North of Ireland. He alluded also to the advantage of being able to 

 get the photographs reproduced in the form of lantern slides, and stated 

 that, if such slides were required for illustrating the physical features of 

 the North of Ireland, he would be able to see that they were supplied at 

 a reasonable price. Mr. A. Tate, on behalf of the Belfast Natural History 

 and Philosophical Society, expressed similar views. 



Professor Meldola pointed out that, in taking photographs of geological 

 sections, in which differences in the strata were often indicated only by 

 small differences in colour, it would be an advantage to use orthochro- 

 naatic plates. The colour differences were sometimes so slight, that the 

 differentiation of strata would be imperceptible in an ordinary photo- 

 graph, and he therefore expressed the hope that the Committee in their 

 schedule of instructions would see their way to recommend the adoption 

 of these plates, which, although somewhat more costly than ordinary 

 plates, would give such superior results as to warrant their use. 



A further discussion took place respecting the desirability of adopting 

 some means by which members of the British Association, and those who 

 assisted in the work, would be enabled to procure copies of the photo- 

 graphs either as lantern slides, prints, or enlargements. Mr. Symons 

 suggested that the best plan would be for those members requiring copies 

 to be allowed the temporary loan of the negative itself, while lantern 

 slides should be prepared by some recognised person under the immediate 

 direction of the Secretary of the Committee. In reply to a question by 

 Mr. M. H. Mills as to whether any underground photographs had been 



