28o 



THE POPULAR SCIENCE MONTHLY. 



Pennsylvania, from near Doylestown to 

 Maryland, and which, taken together with 

 some parallel dikes of similar nature and 

 composition, northeast of Doylestown, forms 

 a series of nearly continuous dikes some 

 ninety miles in length. In the paper he 

 has published on the subject he shows that, 

 although frequently represented only by a 

 line of loose weathered bowlders, it is prac- 

 tically continuous along a course seventy 

 miles in length. In Bucks County the dike 

 abuts against the south side of a great fault 

 of several thousand feet upthrow, and up- 

 ward of twenty miles in length, while, at a 

 distance laterally of five miles, another long 

 dike of identical composition and structure 

 abuts against the north side of the fault, 

 and continues thence to the Delaware River. 

 If not the same dike laterally displaced, 

 the two portions clearly belong to the same 

 system, and were produced by a single cause. 

 It is said that this dike was used during the 

 war of the rebellion by the negro slaves as 

 a guide in their flight northward. Several 

 of the stations of the underground railroad 

 are said to have been on or near its line ; 

 and the negroes were directed to follow 

 these black rocks across fields and through 

 woods "until they were led into the hos- 

 pitable regions of Chester and Bucks Coun- 

 ties." 



The Magnitude of Dr. Gould's Astronom- 

 ical Work. At the complimentary dinner 

 given to Dr. B. A. Gould in Boston, in May, 

 1885, Professor W. A. Rogers, of Harvard 

 Observatory, made a suggestive comparison 

 of the work which Dr. Gould has done at 

 Cordoba, in the Argentine Republic, with 

 similar work done previous to 1S72. There 

 are, he said, in the northern heavens about 

 4,500 stars visible to the naked eye ; while 

 within the same limits there are about 

 95,000 stars as bright as, or brighter than, 

 the ninth magnitude, which are usually ob- 

 served in narrow belts or zones, and are 

 referred to as zone-stars. The bright stars 

 are common to nearly all general cata- 

 logues, but the positions of the fainter 

 stars depend, for the most part, on two or 

 three separate observations. Dr. Gould has 

 formed two catalogues since 1872 a gen- 

 eral catalogue of stars extending to the 

 south pole, containing 34,000 stars, and a 



catalogue of zone-stars, numbering 73,000. 

 The two catalogues represent about 250,000 

 separate observations. It is stated in one 

 of the printed .volumes that the chrono- 

 graphic register of the transits, the point- 

 ing of the telescope for declination, have 

 all been done by Dr. Gould personally. 

 The number of distinct and separate ob- 

 servations involved in this work must cer- 

 tainly exceed a million. The whole num- 

 ber of stars in the two Cordoba catalogues 

 is nearly three times as great as in any 

 single catalogue thus far constructed ; and 

 it must be remembered in this connection, 

 that the great catalogues of Lalande, of 

 Bessel, of Argelander, and of Schjellerup, 

 represent the labors of a lifetime. The 

 total number of stars in all catalogues 

 formed previous to 1870 is about 260,000, 

 as against the 105,000 stars in the Cordoba 

 catalogues. Since 1869, a confederation of 

 fourteen observatories, situated in different 

 parts of the world, has been engaged in the 

 accurate determinations of the positions of 

 the 100,000 stars to the ninth magnitude 

 in the northern heavens. Up to 1882, a 

 total of about 346,000 observations had 

 been made. Considerable progress had 

 been made in this work before Dr. Gould 

 left this country for South America. His 

 work, involving two thirds as many observa- 

 tions as all others combined, is completed, 

 and is all in the hands of the printer, while 

 the actual formation of the catalogue to be 

 issued under the direction of the Astro7io- 

 mische Gesellschaft can hardly be said to 

 have been begun. 



Japanese Camphor. Camphor is very 

 largely exported from the Japanese island 

 of Kiu Shiu, where the tree grows abun- 

 dantly in all situations. Many of the trees 

 reach a great size, some near Nagasaki be- 

 ing said to be ten or twelve feet in diame- 

 ter, while at other places are trees measur- 

 ing twenty feet across ; after forming a 

 trunk twenty or thirty feet high without 

 limbs, the tree branches out in all direc- 

 tions, forming a well-proportioned and beau- 

 tiful evergreen mass. The leaf is small, 

 elliptical, slightly serrated, and of a vivid 

 dark green. The berry grows in clusters, 

 and resembles a black currant. The wood 

 is valuable for cabinet-work and for pur- 



