TRANSACTIONS OF SECTION A. 537 



whicli have proceeded very little further than the preliminary organisation. Some 

 workers have dropped out early in the history of the scheme, some have not even 

 started, and the blanks have not been filled up ; sooner or later — generally sooner — 

 the scheme has been abandoned. The curious may read of some of these schemes in 

 back numbers of the ' Monthly Notices,' thougfh some of them never got into print, 

 and are only to be traced in the Minutes of the Royal Astronomical Society. And 

 yet of many of them, if not all, it may safely be said that a little more energy on the 

 part of somebody would have produced an assured success ; somebody to see that 

 the gaps were tilled up, and dilatory workers hastened or superseded ; somebody to 

 be a sort of foreman of the works. It does not seem unlikely that this general 

 supervision is best performed by one not actually engaged in the work himself — a 

 man of affairs. One of our great London schoolmasters declares that a nominally 

 idle man should be at the head of all enterprises ; that he never knew any good 

 come of any work where there was not ' a man with his hands in his pockets 

 looking after it.' We have scarcely found this to be a necessity in Astronomy j 

 for the men who have looked after the eighteen observatories, taldng part in the 

 Astrographic Chart, have been Directors of the Paris Observatory — men with many- 

 things to claim their attention. To the individual energy of the late Admiral 

 Mouchez and his successors the work owes a great deal. It fell to their lot to 

 overcome the difficulties I have indicated ; to undertake the voluminous corre- 

 spondence necessary at the start ; and to fill up gaps in the ranks of workers. 

 Last July it was found that of the eighteen observatories which had promised to 

 take part, three had made no start ; and M. Lcewy forthwith superseded them and 

 found three others. Thus the risk of incompleteness has been removed ; and we may 

 hope that one danger which threatens such schemes has been successfully averted. 



But the removal of this danger draws our attention immediately to another — 

 that of taking far too long in finishing the work. The project for making the 

 Chart was originally discussed fourteen years ago, in 1887 ; and it was urged by 

 many of those then present that a reasonable time, say ten years, should be fixed 

 for the completion of the whole. In spite of the representations of this prudent 

 minority, the programme was made an ambitious instead of a modest one, and 

 some stretching has been done since, with the result that after fourteen years only 

 one or two observatories are within sight of the goal, the majority seeing from ten 

 to twenty years' work ahead of them ; and, as above remarked, there are three 

 which have not yet started. With this experience we may well ask whether the 

 limit proposed even by the prudent minority was not too high ; and whether it 

 would not be well to fix five years as a limit to any scheme of co-operation which 

 is as yet on paper only. 



The danger of attempting too much is illustrated in a somewhat different way 

 by the Eros campaign. It will be clear from what has been already said that 

 the eighteen observatories responsible for the Chart have their hands quite full ; 

 and now comes a special occasion — an opportunity that will not occur again for 

 thirty years — to determine the Solar parallax. Last winter the newly-discovered 

 planet Eros was known to be coming close to us, and we had an occasion of more 

 value than the Transits of Venus. What were the eighteen observatories to do ? 

 They could not at any rate refuse to take photographs, and this has been done ; 

 even this meant a great deal of additional work for some people for a few months ; 

 but it is a mere tritie compared with the work that is still to come in measuring 

 and reducing the plates, which will be a sensible fraction of the work already 

 projected for the Chart. AVhich is to be done first ? Prudence suggests 

 finishing one entei-prise before beginning another, putting aside the Eros plates 

 until the Chart work is finished. On the other hand there are thirty other observa- 

 tories sharing the Eros work with the original eighteen, and they will be more or 

 less impatient for our results. In this dilemma some rather unsatisfactory 

 compromise will no doubt be adopted, but we may heave another sigh that the 

 advice of the prudent minority in 1887 was not taken, for in that case not one 

 or two but many of the eighteen observatories might have completed the Chart 

 work before Eros came. 



I now pass to a different kind of danger to which co-operation renders us 



