80 



SCIENCE. 



[YoL. VI , No, 129. 



winds for the United States is 28.4 : 9.5, and for 

 the North Atlantic it is 18.0 : 29.8; and this evidently 

 depends largely on the control that land friction ex- 

 erts on wind velocity. 



Fig. 1. — {Section of floating dome at nice. 



— We learn from Nature that the floating dome 

 presented by Bischoffsheim to the observatory at 

 Nice is now finished, and has been recently on exhi- 

 bition in Paris. It is intended to cover a colossal 

 telescope. It is twenty-two metres in diameter in- 

 side, and has a circumference of more than sixty 

 metres, or two metres more than the dome of the 

 Pantheon. Instead of rendering it movable by pla- 

 cing it on rollers, according to the ordinary method, 

 it is closed below by a reservoir for air, which rests 

 on the water in a circular basin (fig. 2). A set of 

 rollers is also placed under the dome to prevent oscil- 

 lation, and for use when repairs are needed. This 

 system of suspension is said to be so perfect, that, in 

 spite of its great weight, a single person can turn it 

 completely round the horizon. To provide against 

 the water freezing, it has been proposed to dissolve in 

 it a salt to the point of saturation, but it is feared 

 that this may cause corrosion of the apparatus. 

 Frosts, however, are rare in Nice, and special experi- 

 ments on this subject will be made. 



— * The germ-theory of disease ' formed the subject 

 of the ' Alumni lectures ' given this year by Dr. W. 

 H. Thomson before the graduates of the Albany 

 medical college. 



— We learn from Nature that Mr. Burbidge, of 

 the Trinity-college botanical gardens, Dublin, points 

 out that Edelweiss is easily grown in English gardens 

 from seed. It is sown in common garden-earth in a 

 cold-frame, and, when large enough, each little plant 

 is placed in a small pot in a mixture of loamy earth 

 and old lime rubbish; or the plants, Mr. Burbidge 

 says, are equally well pleased by a niche in a sunny 

 rock-garden, provided a supply of their favorite lime 

 rubbish or old mortar be afforded them. 



— At the meeting of the Board of visitors of the 

 Royal observatory, Greenwich, the annual report of 

 the astronomer royal was received. In this it is 

 mentioned, that on the publication of Professor Pick- 



ering's * Harvard photometry,' all stars which he had 

 noted as brighter than the sixth magnitude, and 

 which had not been recently observed at Greenwich, 

 were inserted in the working-catalogue, in order that 

 the next Greenwich catalogue might contain all stars, 

 down to the sixth magnitude, which have not been 

 observed at Greenwich since 1860. It is also stated, 

 that, as announced in the Times of Jan. 1, the pub- 

 lic clock at the observatory entrance, and the other 

 mean solar clocks, were put forward twelve hours so 

 as to show Greenwich civil time, starting at midnight, 

 and reckoning from Oh. to 24 h., which would corre- 

 spond with the universal time recommended by the 

 Washington conference. The change from astro- 

 nomical to civil reckoning has also been made in all 

 the internal work of the observatory, and has been 

 carried out without any diflSculty. Greenwich civil 

 time is found to be more convenient, on the whole, for 

 the purposes of this observatory; but its introduction 

 into the printed astronomical observations has been 

 deferred to allow time for a general agreement among 

 astronomers to be arrived at. It is proposed, how- 

 ever, to adopt the civil day without further delay in 

 the printed magnetical results, thus reverting to the 

 practice previous to 1848, and making the time-reck- 

 oning harmonize with that used in the meteorological 



Fig. 2. — Section op float for astronomical dome at 

 nice. 



results, the reckoning from Oh. to 24 h. being for the 

 future adopted in both cases. This was probably the 

 first step taken after the Washington conference in 

 conformity with its recommendations. 



