312 EEPORTS ON THE STATE OF SCIENCE. 



Report of the Conference of Delegates of Corresponding Societies held 

 at Sheffield on September 1 and 6, 1910. 



Chairman ..... Dr. Tempest Anderson. 

 Vice-Chairman . . . . Prof. P. F. Kendall. 

 Secretary . . . . W. P. D. Stebbing. 



First Meeting, September 1. 



The meeting was presided over by Dr. Tempest Anderson, Chairman of the 

 Conference. The Corresponding Societies Committee was represented by the 

 Rev. J. 0. Bevan, Sir Edward Brabrook, Dr. J. (i. Garson, Mr. T. V. Holmes, 

 Mr. W. P. D. Stebbing, and Mr. W. Whitaker. 



The Chairman, after the Secretary had read the report of the Corresponding 

 Societies Committee, opened the Conference by giving the following Address and 

 a demonstration on some methods of optical projection. 



Chairman's Address. 



It is understood that the Sections deal with results of investigations in 

 various branches of science, while this Conference is concerned chiefly with 

 methods of conducting such investigations, and especially in co-ordinating the 

 efforts of our Corresponding Societies in carrying them out. I think we may 

 fairly include in our programme methods of demonstration of such results before 

 audiences, large and small, as questions relating to these constantly force them- 

 selves on the officials of scientific societies. I propose, therefore, to speak on 

 some methods of optical projection to which I have paid attention for many, I am 

 afraid to say how many, years. 



At the meeting of this Association at Aberdeen in 1885 I read a paper in 

 Section C on the ' Volcanoes of Auvergne,' the abstract of which in the Annual 

 Report begins as follows : — 



' The modern dry-plate process of photography has placed in the hands of 

 geologists the power of rapidly and faithfully recording and reproducing before 

 an audience of any size many geological, and especially volcanic, phenomena which 

 it would be impossible adequately to describe in words. 



' By means of the oxyhydrogen lantern a number of photographs which had 

 been taken by the author in the volcanic district^of the Auvergne and adjacent 

 parts of the Velay and Vivarais, in Central France, were shown on the screen.' 



This now reads like a truism. It was then a novelty, and I remember 

 the then President of the Section (Professor Judd) remarking that he thought 

 the process employed might be of value in recording geological, and especially 

 volcanic, facts. Unfortunately the Annual Reports do not contain any account of 

 the discussions following papers, so that I am unable to quote the exact words. 



Three years later, at the Bath Meeting, I read a similar paper on the 

 ' Volcanoes of the Two Sicilies,' which was also illustrated by lantern photo- 

 graphs of Vesuvius, Etna, Stromboli, and Vulcano, and at the same meeting Mr. 

 Osmund W. Jeffs read a paper on ' Local Geological Photography,' in which he 

 urged the importance of the new method. The result was the appointment at 

 the next meeting, at Newcastle in 1889, of a ' Committee for the Collection, 

 Preservation, and Systematic Registration of Geological Photographs,' the 

 valuable results of whose labours are known to you all. 



Projection of lantern photographs is now the recognised method of lecture 

 illustration, and needs no further recommendation : 'Good wine needs no bush.' 



There are, however, cases when the object to be described is of small size, 

 and where it would be convenient to show an image of the object itself. 



Opaque Projection. 



Many attempts have been made to produce an instrument which would project 

 on the screen an image of opaque objects not larger, say, than a postcard, the 



