30 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



Sirius shows, besides Alvan Clark's companion and that of 

 Lassell, eight others within a distance of one minute of arc. 

 12 A, XL, 90. 



THE GERMAN NAUTICAL OBSERVATORY. 



It may be known to some of our readers that since 18G8 

 there has existed in Hamburg a private institution repre- 

 senting the combined nautical and meteorological interest 

 of that city. The control and support of this institution 

 lias lately been assumed by the German Government under 

 the following regulations, among others : By the name "Deut- 

 sche Seewarte " an institution is established whose problem 

 shall be to further the knowledge of the ocean, so far as this 

 is of interest to navigation, as also that of the phenomena of 

 the weather on the German coasts, and to utilize this knowl- 

 edge for the safety and expedition of navigation. The See- 

 warte is located at Hamburg, and has under it nine observ- 

 ing stations and forty-five signal stations along the German 

 coast. The annual appropriation for the entire establish- 

 ment and its dependencies is 75,000 marks. 7 (7, XL, 130. 



THE FIXED HORIZONTAL TELESCOPE OF LALSSEDAT. 



The Siderostat is the name given by Foucault to the per- 

 fected form of the apparatus originally used by Laussedat 

 for photographing the sun. It consists essentially of a 

 clock-work by means of which rotation is given to a mirror, 

 and so uniform and smooth is the movement that for hours 

 together it follows the diurnal movement of the stars with 

 such perfect accuracy that an observer looking into it sees 

 reflected any sidereal object, which latter appears stationary 

 to him while the mirror is moving. Great labor has been 

 spent upon this instrument by Foucault, who has designed 

 it, and by Eichens, who has recently finished its construc- 

 tion. This instrument, as mounted at the Paris Observatory, 

 lias been in constant -use in experiments in photographing 

 the sun ; in fact, it ought to be the indispensable auxiliary 

 of physical astronomy, since it allows the observer to direct 

 his spectroscope or photometer, or other apparatus, steadily 

 in the same direction, viz., toward the mirror, which latter 

 only moves and reflects the sun's rays directly into the 

 optical apparatus. 12 A, X., 358. 



