498 INTERNATIONAL SCIENCE. 



stars appearing on the short exposure photographs. The long expo- 

 sures were intended for reproduction in the form of charts, and are 

 only taken by some of the observatories. As there are about 400 stars 

 on each plate and it takes about GOO plates to cover the share of one 

 observatory once, this means that each observatory has to measure 

 nearly 500,000 star places, and that the complete catalogue will give 

 the positions of nearly 4,500,000 stars. This includes all stars down 

 to the eleventh magnitude. 



The following is a list of observatories taking part in the work : 



For the Northern Hemisphere: Greenwich, Oxford, Paris, Bor- 

 deaux, Toulouse, Potsdam, Helsingfors, Eome, Catania, Algiers. 



For the Southern Hemisphere : San Fernando, Tacubaya, Santiago 

 de Chile, Cordoba, Cape of Good Hope, Perth (West Australia), 

 Sydney, Melbourne. 



The work connected with the ultimate completion of the catalogue 

 and especially the reproduction of the star maps requires considerable 

 expenditure. Each country has to make its own arrangements, which 

 in the British Empire usually means that each body concerned has to 

 pay its own expenses. There Avas, however, in this case, some official 

 help. The Astronomer Royal obtained a contribution of £5,000 

 from the Government for the reproduction of charts, and in the case 

 of the Cape of Good Hope the necessary expenses have been met 

 from imperial funds. Professor Turner, of Oxford, has obtained a 

 grant of £1,000 from the Government grant of the Royal Society, 

 and a further sum of £2,000 for publication from the treasury and 

 the University of Oxford jointly; but the Australian colonies are 

 much hampered by the want of funds, and their work will be delayed 

 in consequence. The four French observatories on the other hand 

 are well supported. Each of them has received a Government con- 

 tribution of £25,700, making a total of well over £100,000. More 

 than half this goes toward the reproduction of the long-exposure 

 photographs as a series of charts, which, however, have proved to be 

 so costly that they will probably never be completed. Indeed, if 

 completed, their utility may to some extent be impaired by the diffi- 

 culty of storing them in an accessible manner. Professor Turner 

 calculates that the series of maps will form a pile of papers 30 feet 

 high, weighing about 2 tons. 



I now pass on to a few examples of undertakings which are 

 intended to fix standards of measurement, or to establish a general 

 agreement on matters in which uniformity is desirable. The fore- 

 most place in this division must be given to the Bureau International 

 des Poids et Mesures, established in the year 1873, at Sevres, near 

 Paris. This bureau was the outcome of an international commission 

 constituted in 1869, which had for its object the scientific construc- 

 tioai of a series of international metric standards. By a convention, 



