HARDWICKE'S SCIENCE-GOSSIP. 



125 



vertical sun, so that it is strange the fish can survive 

 until the water is cooled by the returning tide. 



From a consideration of the formation and position 

 of these "reefs" it seems probable that their forma- 

 tion is due to matter brought down by the rivers, 

 which on entering the sea is drifted parallel to the 

 coast by the prevailing currents. This action is 

 assisted by the constant easterly winds which blow 

 here. Mr. Darwin attributes the formation of the 

 " reefs " of Pernambuco to the action of the currents.* 

 The whole formation is one of extreme interest, and I 

 would commend it to the notice of naturalists who 

 seek for fresh fields of discovery and research. All 

 up and down the coast we have many species of corals 

 flourishing in a warm water current, and yet there are 

 no true reef builders. 



On examining the charts we see the soundings 



The plan shows two sections through the leef 

 carefully drawn to scale, and illustrates clearly the 

 formation of the reef. 



David Wilson Barker. 



A 



ASTRONOMY. 



By John Browning, F.R.A.S. 



T the meeting of the Royal Astronomical 

 Society, held on April nth, a paper ^by 

 Mr. Schaelberle was read on " A Mechanical 

 Theory of the Corona." Photographs were sent] to 

 illustrate the paper, of a ball with many wires 

 projecting from it in curved forms intended to 

 represent the rays of the corona. The theory put 

 forward by Mr. Schaelberle is that the striking 



Fig. 74 —Section across the Reef of Pernambuco, from Arsenal North Boat Basin for 1000 fathoms. 



00 FATHOMS 



Fig. 75.— Section from near Buoy in centre of Mouth of River Beberibe for 1000 fathoms. (Vertical scale 48 times that of 



horizontal. Figures denotes fathoms). 



marked crl. (coral) over a large area up and down 

 this coast even out into deep water, but this is 

 due to large areas of the bottom being covered with 

 Celleporse and Nulliporse. On one piece of cable I 

 picked up, which had been dowji eleven years undis- 

 turbed, the Celleporse had grown on it to a thickness 

 of nine-tenths of an inch ; as it was quite dead, it may 

 have taken far less time than this to attain that 

 thickness. 



Two other places are worth visiting near Per- 

 nambuco, and are easily accessible, thanks to the 

 admirable system of tramways. Dois Irm&os, where 

 are the waterworks which supply the town with 

 drinking-water, and the Red Cliff near Olinda, caused 

 by a landslip, and showing the red marl which is 

 so common over a large part of Brazil. 



* See " Voyage of a Naturalist," p. 498. 



differences which may be observed in the form of 

 the corona can be accounted for if we suppose the 

 axis of the sun to be inclined so that the pro- 

 jecting wires may be seen from different points of 

 view. 



Mr. Wesley said that if Mr. Schaelberle's theory 

 is correct, all coronas observed at the same time of 

 the year ought to be similar in appearance, but that 

 this is certainly not the case, as several eclipses 

 which have occurred in December have presented 

 very great differences in appearance. 



Mr. Maunder read a paper on sun-spots in 1889, 

 in which he said that sun-spots were so sparse in 

 1886 that astronomers generally supposed that the 

 sun-spot period had been reached ; but that since 

 1886 there had been still less solar activity. At the 

 present time, however, there were many signs of 

 greater solar activity. In 1886 the average duration 



