108 SCIENCE PROGRESS 



them. The attendance was sufficient to encourage the hope that a continuance of 

 the meetings will be arranged for next winter. The Committee have under con- 

 sideration the question of placing the project on a more permanent basis, and also 

 the question of arranging for the publication of papers presented at the meetings. 

 At present there is no means of publication, and so original papers are not 

 presented. The first series of meetings was devoted mainly to the presentation of 

 accounts of work up to the present time in various subjects ; these have not been 

 published in detail, although of great value, but abstract reports of some length 

 were given in the Observatory. It is to be hoped that it will be found possible to 

 place the scheme on a basis which will ensure its future success : a great step 

 towards the advancement of geophysical study in this country will then have 

 been taken. 



The Commencement of the Astronomical Day (H. S. J.) 



It is probably known to most people that the astronomical method of reckoning 

 time differs from the civil, the civil day commencing at mean midnight, whilst the 

 astronomical day of the same date commences at the succeeding mean midday. 

 The question as to the desirability of the uniform adoption of the civil day for 

 both civil and astronomical purposes is one which is raised periodically. Laplace 

 proposed the unification of the two systems as long ago as 1804, and his proposal 

 was agreed to by the French Bureau of Longitudes, but no action was taken to 

 carry it into effect. In 1884 the question was raised afresh at the International 

 Congress at Washington, which decided in favour of unification. At a Congress 

 at Geneva in the following year the resolution of the Washington Congress was 

 the subject of a long discussion, and mainly through opposition from the German 

 astronomers the matter was allowed to drop. The question was raised afresh a 

 few years later by the Astronomical Society of Toronto, and again the French 

 Bureau of Longitudes approved of the change. An able report on the pros and 

 cons of the case by the late M. Poincare is contained in the Annuaire of the 

 Bureau of Longitudes for 1895 (a translation was given in the Observatory, &, 323, 

 September 1917). For the change to be of value it is necessary that it should 

 be adopted simultaneously by the Governments which publish the principal 

 ephemerides. This agreement has not hitherto been obtained. 



The question has recently been once again brought forward by the Astronomer 

 Royal and Prof. Turner. It may be thought that the question is one of mere 

 academic interest. This is not so, as it would affect the various Nautical Almanacs. 

 The change, in fact, is now advocated on account of the simplification which would 

 result to navigators, who find the present system confusing and liable to lead to 

 mistakes. Thus Capt. Fulton, of the Board of Trade, gives the following instance : 

 To find the Greenwich date of the Moon's meridian passage on board ship, *« one 

 must enter the Nautical Almanac under the heading Meridian Passage (Upper), 

 and, if in West Longitude, take the difference between the time of passage on the 

 given day and the day following, or, if in East Longitude, take the given day and 

 the preceding day, using simple proportion to find the time of passage at ship. 

 This is a simple operation and easily remembered, but, as it refers to astronomical 

 time, the observer must remember that the Moon passes the meridian after 

 midnight during the half-lunar month, and he must, therefore, note whether the 

 observation is A.M. or P.M. As an example, suppose a ship in West Longitude on, 

 say, the 16th July a.m., at ship then the dates for the meridian passage will be the 

 15th and i6th,and in East Longitude the 15th and 14th." It can readily be under- 



