NATURE 



[Sept. 1 8, 1884 



passed the boat, which rose and fell to them as they swept on. 

 Ahead was the small island near the north-west entrance to 

 Oban Harbour ; Ken-era Island was close on the right or star- 

 board bow. The sea was so calm, there was no sign of wash on 

 either shore. As the wave rolled in I watched it, and after a 

 few seconds the white line of surf became visible and the noise 

 of the same following told of its breaking on the rocks with some 

 violence. It was not the wash of any steamer, as the boatman 

 at first unthinkingly surmised, for in the first place it was too 

 broad a dome of water, many of our boat's lengths, into which 

 the few short waves even of the largest steamers could not 

 resolve themselves ; secondly, there was no steamer in sight, nor 

 had any lately gone by, save the Duke of Argyll's steam yacht, 

 which had passed near us more than half an hour previously. 



Such a wave could not have originated in the narrow channel 

 between Mull and the mainland, but must have come in from 

 the Atlantic, and had its origin, I imagine, in some far distant 

 submarine disturbance. I have seen a report in the papers of an 

 earthquake in Jersey, and I am informed by some friends lately 

 returned from Cornwall (near St. Michael's Mount), that on 

 August 26, about 4 p.m., when watching a seine net being pulled 

 ashore, a wave larger than usual — described as a long black line, 

 seen for a long time — rolled in. Perhaps others may have noted 

 similar waves at other parts of the coast, and been able to 

 record the exact time. H. H. Godwin-Austen 



Deepdale, Reigate, September 9 



Salmon-Breeding 



On August 28 an examination was made at Lord Lauderdale's 

 fish-rearing ponds at Howietoun into the condition of the young 

 salmon and hybrid Salmonidte, and with the following interest- 

 ing results : — 



A hybrid was taken from Pond No. 3 which measured 6 5 

 inches in length ; it was one of about 190, all much the same 

 size, which were raised from the eggs of the Lochleven trout 

 fertilised from the milt of the American char, Sahno fonlinalis, 

 on November 15, 1882. The specimen was a male with the 

 milt nearly fully developed ; the fish would evidently have bred 

 this winter. 



A hybrid was removed from Pond No. 4 which measured 7 '5 

 inches in length ; it was one of about 90, and raised from the 

 ova of the American char milted from a Scotch char from Loch 

 Rannock on November 15, 1882. It also was a male with the 

 milt as fully developed as in the preceding hybrid. 



Segregation in these ponds has been most rigidly carried out, 

 and the results show that trout and char, or two species of 

 char, will interbreed and give fertile offspring. A lew more 

 months will decide whether the females are as forward as the 

 males, and whether the milt itself is prolific or not so ; also to 

 what extent hybrids will interbreed. 



A hybrid was removed from the Octagon Pond at Craigend 

 which measured 65 inches in length; it was one of 212, 

 and raised from the ova of the Lochleven trout, fertilised by 

 salmon milt on December 24, 1S81. It was a barren female ; 

 whether any will be fertile time will show. 



A grilse was taken from the salmon pond at Howietoun which 

 measured fourteen inches in length ; there are a large number, 

 but they are in too deep water to count. These fish were raised 

 from the ova and milt of pure salmon taken from the Teith in 

 December, 18S0. The specimen was a female, with the ova 

 well advanced, being o - i inch in diameter, and would have bred 

 this season. This fish was well nourished, with eleven rows of 

 scales between the adipose dorsal and the lateral line, and sixty 

 Cffical appendages. This solves the question that our salmon 

 may not only be reared in a healthy state in suitable ponds of 

 fresh water, but also, if properly cared for, will breed without 

 descending to the sea. Last year the milt of the pars from this 

 pond were successfully used for breeding purposes. 



Francis Day 



Hydrodictyon in the Eastern Counties 



It may interest some of your readers to know that Hydro- 

 dictyon utriculalum (Roth), reckoned by Dillwyn among the 

 rarest of the fresh-water Alga;, and now gen. rally described a 

 confined to the ditches and pools of the Midland and Southern 

 Counties of England (W. J. Hooker, 1833 ; Harvey, 1841 ; 

 1 la, -all, 1845; and Griffith's " Micrographical Dictionary,' 

 1S83), can again be claimed a- an inhabitant of the Eastern 



Counties. A few days ago I found a fine and well-grown 

 specimen in the river just above the well known sluice at 

 Denver. 



In the earlier half of the present century Cambridge seems to 

 have been the centre for its distribution. Dillwyn, in 1809, 

 relates that he received his specimen from the pool of the old 

 Botanic Garden. Harvey, in 1841, says that he has fine speci- 

 mens from Prof. Henslow, gathered in a pond in the Botanic 

 Garden at Cambridge, where the plant has existed for many 

 years. Ilassall, in 1845, repeats Harvey's words, again on the 

 authority of Prof. Henslow. Since that time it appears to have 

 become completely extinct in this neighbourhood. The Curator 

 tells me that two or three years back an attempt was made to 

 introduce it into the pond of the new Botanic Garden, but with- 

 out success. It is, I think, therefore worthy of record that this 

 remarkable plant, so interesting to the biologist, has been lately 

 discovered, apparently naturalised, at the bottom of the Ten 

 Mile River, about twenty yards from the tidal waters of the 

 Ouse. 



The reappearance of Hydrodictyon on the fens round Cam- 

 bridge is also interesting from the hope it inspires that, owing to 

 the increased facilities for investigation now afforded by the 

 University, further light maybe thrown upon its singular cycle 

 of development which, notwithstanding the labours of Areschoug, 

 Cohn, Pringsheim, and others, must be said to be still somewhat 

 obscure. J- C. Saunders 



Downing College, Cambridge, September 4 



The Sky-Glows 



The sun-glow phenomena have entered upon such a fresh 

 phase that I venture to send some extracts from my notes. It is 

 not simply a renewal of the sunsets of last season, although that 

 in itself will doubtless seem remarkable to those who have not 

 noticed the almost constant occurrence of the "day glows" 

 throughout the summer ; the chief point is the radiating 

 character. a 



September 11. — Glow 6.50 p.m. At 7 a vertical bar 2 to 3 

 across at base, to altitude 20 . Another at angle 45 to north ; 

 at 7.3 a third at angle 30° to north. The three faded at 7.5, 

 7.7, and 7.10. 



September 12.— Sun seen to set by 6.20. At 6.35 ruddy tint 

 above earth shadow in east ; gone at 6.45. 6.50, fine glow from 

 north-west to south-west, up to 30° ; 6.55, very fine, up to 35°; 

 much purple. Gradual change to low orange glow by 7.4, this 

 fading by degrees, but partial return at 7.9 ; little left at 7.19. 



September 13 (sunrise).— 4.57 a.m., lovely orange glow and 

 reflection in west. Cirri bright. 5.0, pink shot up vertically 

 (in inverted pyramid) to height of Jupiter. 5-oi, bar at angle of 

 45° to north. 5.5, whole north-east to south east suffused, 

 broken by dark bars, four to north, five to south, radiating from 

 sun. Central mass now 5* to 10° above Jupiter. Cirri now 

 dark at east, but slight tint near Venus (these proved to be 

 higher and more feathery, the others about 7° or 8° above east by 

 north, approaching to cirro-strati). 5.7. now five bars to north, 

 seven to south. Light wider spread, now to level of Venus 

 (roughly measured as 35 ). Soon traces even to 45 . Bars very 

 marked ; one from east-north-east reaches north-north-east, at 

 altitude about 22 . Low cirri now re-lit. 5.15, whole mass 

 now barred ; nine to north, and two new ones to south of centre, 

 but lower part to south now gone. Cloud over Venus now re- 

 Ik. 5.20, going to west window find marked counter-glow, also 

 liarred, radiating from perspective just like bands of cirrus, yet 

 marvellously clear sky. Four dark bands to south, five to north, 

 wider than those seen in east, and definition much less distinct. 

 Rosy tints now gone. A ruddy tinge almost from south to north 

 above earth-shadow, except just south of due west, whence rose a 

 broad dark vertical bar. Faint cirri to south now lit up. 5.28, 

 bars to north and south still visible, and no glow above earth- 

 shadow at anti-solar point. Glow lasting at 5.30. Cirri in east 

 quite dark again, but the cirri near Venus and to south white. 

 Former now in vertical lines, but upper edges blown in wisps 

 towards north. 5.40, stratus low in east by south. A greenish 

 cast given to Venus and Jupiter when the glow strongest. Rosy 

 glow at limes noticed during the day. Sun rose about 5.50. 



Sun set before 6.20.— 6.35, ruddy tinge along east horizon, 

 keeping above earth-shadow as it ascends. 6.45S, cirro-stratus 

 5° to IO° above horizon, due west again lit up bright (first at 

 6.30) for two or three minutes, quickly followed by rosy glow in 

 clear sky, as three central bands, divided by narrow dark bars, 



