52 REPORT 1871. 



seen. The periodic time of 27| years is well indicated by these dates, 

 thus : — 



A.D. 288 to 1439 42 periods of 27-405 years each. 



1439 to 1743 II 1. 27-636 „ 



1743 to 1798 2 „ 27-500 „ 



" If these periods are correct, it is a remarkable coincidence that the 

 aphelion distances of the meteoric rings of April 18th-20th, October 15th- 

 21st, November 14th, and December llth-13th, as well as those of the 

 comets 1866 I., and 1867 I. are all nearly equal to the mean distance of 

 Uranus." 



4. Beitriige zur Kenntniss cler Sternschnuppen, von Dr. Edmund Weiss 

 (Sitzungsberichte of the Imperial Academy of Vienna for January 16, 1868) 

 presents a short summary of the mathematical problems required to be 

 solved in the determination of the parabolic orbit, and the actual relative 

 speed of the meteors' course in the atmosphere, from the known position of 

 the radiant-point ; and shows how approximate calculations of the velocities 

 of shooting-stars have led to discoveries, in proving certain periodical meteor- 

 currents to be intimately connected with comets of which the orbits have 

 recently been determined*. 



5, The Fuel of the Sun, by W. Mattieu WiUiams, F.C.S. (8vo, 222 pp. 

 Simpkin and Marshall). — An attempt to explain convulsions of the sun's sur- 

 face by planetary disturbances of a universal atmosphere collected in greatest 

 density about the larger bodies of the solar system, and agitated by tides 

 arising from their several attractions, is the theory for the establishment of 

 which a collection of the greatest interest of recent observations of solar 

 physics has been brought into a small compass by the author of the work, 

 and is well directed to explain the chief phenomena of solar physics. The 

 corona is regarded (Chapter XIII.) as originating in solar projectiles driven 

 from its surface with eruptive violence. In the following chapter the source 

 of meteorites is conjectured to be the solar projectiles which thus pass beyond 

 the boundaries of the zodiacal light ; some of which being confined to revolve 

 in two principal orbits outside of that luminary, and in several intermediate 

 zones of irregularly and more thinly scattered projectiles, may be regarded 

 as giving rise to the August and November, as well as to other minor and 

 more or less regular meteoric displays. Somewhat more important specu- 

 lations and descriptions of the meteorology of the moon and planets, as well 

 as of the distribution of the nebulae, suggesting the stellar origin of some of 

 those bodies, occupy the greater portion of the remainder of the work. 



* The velocity of the April meteors, or Lyraids, of the 20th of April meteoric shower, 

 relatively' to the earth, is given in Dr. Weiss's list of radiant-points and relative velocities of | 

 coraetary orbits, in the above paper, as 1-585, that of the earth in its orbit being unity. 

 Adopting the value of 18-6 miles per second for the earth's mean orbital velocity, this gives 

 the relative velocity of the Lyraids, or April shower-meteors, 29-5 miles per second ; very 

 nearly that observed (30 miles per second) in the case of the only shooting-star of the shower 

 doubly observed, as described in this Eeport, on the night of the 20th of April last. 



