42 



HARBWICKE'S SCIENCE-GOSSIP. 



" Herr Professor Bailey in West Point, New York, der 

 fliissige amerikanische Freund mikroscopischen For- 

 schung, hat dem Vorfasser eine Probe einer Erdevon 

 der Bermuda Inseln zugesandt, dass er dieselbe mikro- 

 scopische analysiren und der Inhalt zu organischen 

 Formen namhaft machen undbestimmen moge. Ihm 

 ist sie von Herrn Tuomey aus Petersburg in 

 Virginien mit andern Erdarten zugekommen." It is 

 certain that Professor Ehrenberg jumped to the con- 

 clusion that the deposit was from the Bermuda 

 Islands. I saw many years ago a small packet of the 

 deposit in question, which had been sent by Professor 

 Bailey to Mr. Brightwell of Norwich ; it was labelled 

 " Bermuda Tripoli, J. W. B.," nothing being said 

 about islands, and in spite of the close resemblance 

 this deposit bore to the other Virginian earths, we 

 all fell into the same error as Ehrenberg ; it is pro- 

 bable that Bailey himself knew no better, as he does 

 not appear to have ever corrected Ehrenberg's mistake. 

 I am convinced that a similar mistake has been made 

 with regard to the Moron deposit, which Greville 

 says came from Spain. Judging from the resem- 

 blance the forms found in it bear to those in the 

 Californian deposits, I think there can be little doubt 

 that it came from some obscure place of that name 

 in California. It has always been a matter of surprise 

 to me that Ehrenberg should have figured so few of 

 the beautiful forms more or less plentiful in the 

 Bermuda deposit, particularly as the "Mikrogeologie " 

 was not published until 1854. The species of Helio- 

 pelta he figured and described are H. Melii (named 

 after Jacob Metius, inventor of microscopes, 1606). 

 II. Lceuivenkoekii (named after the celebrated micro- 

 scopist, 1675) with 8 divisions : Monatsb. and Mikro- 

 geo. Pritchard says it has 10. II. Eulerii (named 

 after Euler, the famous optician), with 10 divisions : 

 Monatsberichte ; Pritchard says 12. II. Selliguei (not 

 Selligurii) (after a maker of improved microscopes), 

 with 12 divisions ; Pritchard does not give the number 

 of divisions, but spells the name erroneously (Seli- 

 querii). //. Dol/ondii was first published in the 

 Mikrog. (p. 263) but not figured. It is now generally 

 admitted that there is not sufficient difference between 

 Heliopelta and Actinoptychus to warrant the constitu- 

 tion of a new genus, or that the number of " divisions" 

 are of any specific value. Omphalopelta versicolor is 

 the internal plate of Heliopelta. Frustules of Aulaco- 

 discus margaritaceus not unfrequently occur with the 

 processes differing in number on the opposite valves, 

 and a few days ago I picked out a frustule of Cos- 

 cinodiscus piinctatus. Ehr. (oval var.), the valves of 

 which separated in mounting. One of them has the 

 granules somewhat dtnsely packed, in the other they 

 are close near margin, but scattered as they approach 

 the centre. — F. Kitton. 



Mourne Diatoms. — Ehrenberg first described the 

 Mourne mountain Diatoms in the Monatsberichte 

 for 1842, and in the Mikrogeologie tab. xv. is de- 



voted to the forms found in this deposit, which he 

 says is from Mourne Mountains, Down, Ireland. In 

 1867-8 Dr. Arnott and myself wanted to obtain some 

 of this material, but were unable to do so, and we 

 came to the conclusion that Ehrenberg's sample, re- 

 ceived from the Countess of Caledon, was marked 

 " Mourne " only, and was really the deposit from 

 Lough Mourne, co. Antrim (sold as Lord Roden's 

 Plate Powder), which he erroneously supposed came 

 from the Mourne Mountains. In support of this ex- 

 planation is the fact that the forms he figures are 

 those occurring in Lough Mourne, such as Surirclla 

 Caledonica (named after the Countess), Campylodiscus 

 Hiberiicus, Sec. &c. — F. Kitton. 



Greenwich Microscopical Society. — "At the 

 Annual Meeting, held at the lecture hall on the 20th 

 December last, Mr. George D. Colsell, of 5 Hamilton 

 Terrace, Hyde Vale, Greenwich, was elected Hon. 

 Secretary of this Society." 



Magnifying Measurements. — Will any of your 

 more experienced readers kindly explain a difficulty ? 

 I cannot quite understand the magnifying measure 

 of diameters as used in Microscopy. I have hitherto 

 supposed that any object magnified, say 100 diameters, 

 would appear 100 times as long and 100 times as 

 broad as its real size. But when using the 

 combination of I inch objective with B eye-piece, 

 by a celebrated maker, said in his list to magnify 

 seventy-six diameters, and using the stage micrometer 

 as an object — the T J D of an inch divisions only appear 

 to be one-third of an inch long, instead of, as I 

 expected, T 7 iK>> tnat * s > three-quarters of an inch — a 

 very considerable difference. Thus three magnified 

 divisions of the micrometer appear to go to an inch, 

 instead of one division going to three-quarters of an 

 inch. I have hitherto thought that when each 

 division of the micrometer (iooths), drawn by the 

 camera lucida, measured one inch on the paper, the 

 figure was magnified 100 diameters (X 100) ; but if 

 this were so, each division, when viewed by a 

 combination magnifying seventy-six diameters, that is, 

 J of ICO diameters, would naturally appear f of an 

 inch, instead of, as it does, appearing l. I shall be 

 greatly obliged if any of your readers who under- 

 stand the subject will explain my difficulty. — 

 E. A. C. H. 



Canada Goose. — A few of these birds are shot 

 along the south coast most sharp winters ; it must 

 not be supposed, however, that these come from 

 Canada. The bird is easily domesticated and agrees 

 well with common geese, and may be found in many 

 private grounds in England. It has long been 

 naturalised in many parts of France, as both Buffon 

 and Bewick speak of it as being common there. It 

 is most likely that the bird referred to came from 

 France, as during the prevalence of S.E. winds many 

 wild fowl common to the French coast are to be met 

 with in our own southern estuaries. — F. Cliurton. 



