PHOTOGRAPHY AND ASTROPHYSICS 441 



in this direction, if adequate opportunity and inducement were 

 provided. Could not a part of the sums available for the endowment 

 of research be devoted to the endowment of text-books? It is, of 

 course, an inducement to write such a book that it is a good thing 

 well done; but in the case of a scientific worker this is scarcely 

 sufficient, because the same could be said of his continuing his particu- 

 lar work. If we ask him to pause, and render the treasures he has 

 collected accessible to others, there must be some additional induce- 

 ment. Publishers are not able to offer pecuniary encouragement, 

 because books of the type I have in mind would not appeal to a very 

 large public. But why should they not be subsidized? I do not think 

 it need be a very costly business, if the money were placed in the hands 

 of a central body to issue invitations for books to be written. An 

 invitation would be in itself a compliment; and the actual pecuniary 

 value of the inducement would shrink in importance, just as the 

 actual amount of gold in a medal awarded by one of our leading 

 scientific societies is not very seriously regarded. It may be objected 

 that to ask the best men to write text-books is to set them to inferior 

 work, and so to delay true scientific progress; but are we sure that 

 the real march of science is being delayed? There are pauses in 

 a journey which merely waste time; but there are others without 

 which the whole journey may be delayed or prevented, as when 

 a man should neglect to rest and feed the horse which carries him. 



But the development of photography has brought with it much 

 more than a recurrence of diffidence in some amateurs; it has fore- 

 shadowed a serious rearrangement of astronomical work generally, 

 a new division of labor and a new system of cooperation. To 

 quote one notable instance: a very small number of observatories 

 could take enough photographs to keep the whole world busy 

 examining or measuring them, and we are already face to face 

 with the question whether this is a desirable arrangement. Let 

 me give a concrete example of this modern situation. In the winter 

 1900-01 the small planet Eros offered a specially favorable oppor- 

 tunity for determining the solar parallax, and some thousands of 

 photographs were taken at a number of observatories for the purpose. 

 It is not yet very clear how a definitive result will be obtained from 

 the mass of material accumulated, most of which is being dealt with 

 in a very leisurely manner: but a small portion of it has been dis- 

 cussed by Mr. A. R. Hinks, of Cambridge, and one of the many im- 

 portant results obtained by him in a recently published paper (M on. 

 Not. R. A. S., June, 1904) is this: that the plates taken at the Lick 

 Observatory are susceptible of such accurate measurement, and so 

 numerous, that a determination of the solar parallax from them alone 

 would have a weight nearly equal to that from the whole mass of 

 material. If the Lick plates can be measured and reduced, it will not 



