460 



KNOWLEDGE & SCIENTIFIC NEWS. 



[June, 1906. 



and it was ijarliciilarly iiotiood thai wIicti ihi- lava-slreanis 

 ■surroundcil tries many of lliost' \v hiih stood upright 

 amoiifisl the hoi lava nlaiiicd lluii- Ir.iM-, and hlossonis 

 apparently uninjured. 



Changes in the Sea Level. 



As sliowinj:;' ])ossil)ly some submarine action in tin- \\a\ of 

 subsidence of tiie t)e(l of the sea, it was noticed thru llie 

 sea-level was lowered, on the ylh and Slh of Aiiril, six 

 iiuhes, near l'u//uoli, and as much as twelve inches near 

 l'orli( i, ami it had not returned to it,s previous level on 

 April iS. More information on this head is certainly 

 d( sirable. 'l"he alteration of a sea-level in a small tract, not 

 observed beyond that tract, cannot remain permanentlv, and 

 il .remains to be seen whether the sea will resume its 

 position. Otherwise, should it not prove to be the troutjh 

 of a hui^e w.-ive-imdulation, wliich would afterwards chanf^e 

 to a devastating; wave thrown upon the land, the cause 

 must he looked for in an elevation of the co.ast-line in 

 question. It will have been noticed that Pu/zuoli is one 

 of the places to which reference is made, and the instance 

 of the subsidence and subsequent re-elevalion of the 

 columns of the temple, said to have lieen dedicated to 

 Jupiter .Serapis, will at once come to mind, as havini; oc- 

 curred at the same place. 



Those who remembered the fine sunsets which occurred 

 after the eruption at Krakatoa, in 1883, were on the watch 

 for similar phenomena in .\[)ril. Nor were they altogether 

 disappointed. .Some very fine sunsets were seen, but col- 

 lected information on this head is required. Our readers 

 will perhaps bear in mind that we shall be glad to receive 

 records of such sunsets, wilb lime, date, and jilaci' where 

 observed. 



Foreign Boulders in the Chalk. 



Mr. G. E. Dihley, F.(i.S., has been fortunate in dis- 

 covering a fine mass of quartzite, weighing three pounds, 

 in the chalU of .Strood. -The question of the method by 

 whicli I his and similar erratics were carried and dropped in 

 the chalk-sea is a fascinating one. Various means have 

 lieen suggested. Convevance by means of ice is a likelv 

 explanation, whilst it has also been suf'^srested that they 

 may have been carried out to sea, entangled in the earth 

 at the roots of storm-tossed trees wrenched from the soil 

 of a neighbouring coast. .Mr. Dibley's exploration of the 

 chalk at Burham, near Rochester, has also resulted in the 

 discovery of a fine set of teeth of I'li/rhadiix dirnnrns, Aq. 

 {var. drprcssiix), from the zone of ITi'lasfrr .ftih-filiilmmn;. 



ORNITHOLOGICAL. 



By W. P. PvcRAFT, A.L.S., F.Z.S., M.B.O.U., &c. 

 Ducks assuming Drakes' Plumage. 



Di^. C. G.Si LiGMANN, the Pathologist to the Zoological Society, 

 contributes an extremely interesting article to the columns of 

 theF;V/if, May 12, on the subject of the assumption of the male 

 plumage by female ducks. 



His observations were made on two domesticated birds, and 

 extended over a considerable period. In both cases these 

 birds for several years laid eggs and reared broods, but sud- 

 denly became sterile and gradually assumed the plumage of 

 the drake, even to assuming the characteristic "eclipse" 

 plumage. One of these birds, it is significant to note, did not 

 enter on this abnormal phase until ten years of age, and the 

 other at five years of age. 



Both birds, on assuming the drakes' livery, refused all inter- 

 course with males, but what is more curious, they assumed the 

 conduct of males towards the females with which they were 

 penned. 



'As it has been found inconvenient," remarks Dr. Seligmann, 

 •' to have no single word to describe a bird which has assumed 

 the plumage of the opposite sex, whether of the female or the 

 male, or vice versa. ... I have ventured to term such 

 birds alopterotic (SXKoS:, other : TrepuiToi;, feathered)." 



Bittern in Devon. 



Mr. C. H. Calmady-f^amlyn in the Field (April 14) tells how 

 he unintentionally shot a IMttern [Bolntirm slelUuis) at 



Bridestowe, Devon, on January 11. Hefired through a clump 

 of thorns at what he believed to be a wild duck, but found on 

 recovering his victim a Bittern. Fortunately the bird was 

 only very .slightly wounded in the wing. He therefore took it 

 home and kept it a few days in his garden, where it quickly 

 recovered and ultimately look its departure. The bird has 

 since been seen several times by a friend of Mr. Hamlyn's, 

 and it is hoped was not eventually killed. 



Hoopoe in Kent. 



The appearance of a Hoopoe on a garden lawn in Kent is 

 certainly worthy of record. Mr. .A. Randall Davis, who had 

 the good fortune to be thus favoured on April 6, .accordingly 

 sent a short account thereof to the Field (.April 14). The bird 

 st.ayed until the Sth and then vanished; but during its stay 

 appeared very tame, though mobbed at first by thrushes, 

 blackbird?, .and jackdaws. After an hour or two, however. 

 " all had settled down (luietly together." With a little 

 encouragement, as we h.ave before remarked, it is possible 

 that this bird might be induced to live here regularly. 



The issue of the Field for the following week (April 2t) 

 brought a note from Mr. Charles Ticehurst, who saw a Hoopoe 

 on the Golf Links at Rye on April 7. Thus, if these birds 

 escaped the gunners, it is possible that chance may have 

 brought them together, since Hythe is not far distant, and in 

 that case, assuming them to have been a pair, we may yet 

 hear of another instance of the Hoopoe nesting in England. 



Lapwings Swimming. 



Though not generally known, it is a fact that the Lapwing 

 (Vanellus crisUitus) frequently takes to the water. On one 

 occasion indeed a flock were observed resting on Lough Derg, 

 CO. Limerick, two miles from land, the wind blowing hard 

 from the east. Apropos of this, Mr. H. W. Robinson con- 

 tributes a note to the Field (April 21) to the effect that he has 

 seen " young lapwings not long hatched swimming about in 

 ditches like ducklings, and jhas] also seen them land after- 

 wards and run up to their parent." This fact is probably 

 new to most of our readers. 



Nesting of the Egyptian Plover. 



The remark.-ible nesting habits of the I-'gyptian Plover 

 (Phtvimuts cri^yplius) arc by no means yet thoroughly under- 

 stood. This bird has a habit of burying its eggs in the sand, 

 but whether covered for the purpose of concealment, as the 

 Grebes cover their eggs when leaving them, or whether they are 

 left to be incubated by the heat of the sun, is not yet certain. 

 Nor is it known whether birds which have been seen sitting 

 on these eggs have first uncovered them, or whether, as has 

 been suggested, they are merely- protecting them from the in- 

 tense heat of the sun. In the current number of the Aviciil- 

 tural M(if;nziiie, Mr. \V. G. Percival contributes further testi- 

 mony as to the burying of the eggs, but does not offer any 

 suggestions on the above points. 



Arrival of Summer Birds. 



Going to Press early last month on account of the Easter 

 holidays, we were unable to bring our list quite up to date, 

 and herewith add a few further notes : — 



Swallow — Seaton, Devon, April 3 ; Newhaven, Sussex, 



April 5. 

 Nightingale — Cafcrham, Surrey, April 7. 

 Black Cap — Stroud, Gloucestershire, April Ti. 

 Whitethroat — Lancaster. April S. 

 Sedge W.arbler — Market Harborougb, April 13. 

 Cuckoo — Surrender Park, Kent, April 11. 

 Wryneck — Guestling, Sussex, April 5; Cranbrook. Kent. 



April 6. 

 Nightjar — North Finchley, April 2<S. This abnormally 



early record is commented upon by Mr. W. B. Tcget- 



meier in the Field, May 12. 



PHYSICAL. 



Bv Alfred W. Porter, B.Sc. 



Absorption of Alpha Streams. 



The woik on the products of Radium is now necessarily one 

 of detail, in which g.ips are being filled up or laws supple- 



