ASTRONOMY AND METEOROLOGY. 379 



gous to those which distinguish the well known variable star Algol On the 

 19th of December, 1852, he perceived the star when its light was very faint. 

 The interposition of clouds prevented him from observing the precise instant 

 of minimum brightness, and when the sky again cleared up, the light of the 

 star had already sensibly increased. He is of opinion, however, that the period 

 of variation as ascertained by him, viz., nine days, eleven hours, thirty-seven 

 minutes, can not differ more than two minutes from the true value. All his 

 observations of the star since February 16th, 1850, agree very well with this 

 determination ; but he has not yet succeeded in observing an exact minimum. 

 As the star affords a visible minimum only every nineteen days, there is little hope 

 of a single individual accomplishing much" by means of such observations, and 

 it were therefore desirable that other astronomers should direct their attention 

 to this remarkable object. A five-foot Fraunhofer, or even a four-foot instru- 

 ment with a dark sky, will suffice for this purpose, and the star is easy to find 

 by means of its situation with respect to Prcesepe and Cancri. 



OX THE XUMBER OF THE DOUBLE STARS. 



In the great work which Mr. Struve has lately published, containing the 

 record of his labors on Double Stars at Dorpat, he gives, as the result of his 

 careful examination and comparison of the whole body of facts in stellar as- 

 tronomy, some conclusions of a novel character respecting the number and 

 constitution of the double, or multiple stars. He examines especially the 

 brighter stars those comprised between the first and fourth magnitudes 

 and arrives at the conclusion that every fourth star of such stars in the heavens 

 is physically double. He even ventures to assert that when we have acquired 

 a more complete knowledge of double stars, it will be found that every third 

 bright star is physicall} r double. Applying these considerations to the stars 

 of inferior orders of magnitude, he finally arrives at the following conclusion, 

 which he admits to be of an unexpected character : that the number of in- 

 sulated stars is indeed greater than the number of compound systems; but 

 only three tunes, perhaps only twice as great. 



ox THE ADAMS'S PRIZE PROBLEM FOR 1857. 



At the last meeting of the American Association Professor Peirce, of Har- 

 vard, submitted some remarks on the above subject. The problem has for its 

 subject the Motion of Saturn's Rings, allowing them to be solid or fluid, 

 concentric or eccentric. Professor Pierce disapproved much of this sort of 

 prizes that wasted all the minds but one that were occupied with them, and 

 still more so when they were limited to the graduates of a single university, 

 as to that of Cambridge, England, in this instance. He reserved the consider- 

 ation of solid rings of immovable parts for a meeting of the Mathematical 

 section, when by use of formulas he would prove it untenable. Can it be 

 made up of a mass of satellite movable among themselves ? Then they must 

 be in continual motion among themselves, revolving among themselves about 



