January, 1907.] 



KNOWLEDGE & SCIENTIFIC NEWS. 



23 



sees it when washing and floating the gfatherings. I 

 should think that 50 or (So per cent, of the sand is com- 

 posed of the empty shells." In a further letter, Mr. 

 Heath says : " With reference to pro<-uring supplies of 

 dredging-s and ocean ooze, one of the best plans I 

 know of is to get in with an ofBcer of one of the cable- 

 laying steamers, which take soundings in great depths. 

 I have so far failed myself to get to know one, but hope 

 some day I may do so. I have had a lot of very ex- 

 cellent rnaterial, however, from the steam trawlers that 

 work out from Cardiff. I wrote to a member of one 

 firm asking him if he would kindly allow me to board 

 his trawlers when they arrived in, to .scrape the sand 

 from the crevices of the trawls, and he most kindly 

 gave his superintendent instructions that I was to have 

 everv facility, so that I collected from the different 

 trawls from prettv nearlv all the grounds they visited, 

 including off 'the Smalls'; off 'The Wolf; the 

 Atlantic^ 150 miles west of I.undy; off the Basketts 

 (Cape Clear, S.W. Irish coast); 30 miles S. of Kinsale 

 Head; off Ushant, Finisterre, &c. I also had some 

 very fine material collected by an officer on H.M.S. 

 Euryahis when on the Australian station. These in- 

 clude Broken Bay, Hawkesbury River, N.S.W., 7 

 fathoms; Largs Bay, S.A., 6 fathoms; Auckland, N.Z., 

 6 fathoms; Port Lincoln, S.A. (poor), q fathoms; Hob- 

 son's Bay, Melbourne (verv poor), 5J fathoms; Sydney 

 Harbour, X..S.\V. (verv rich), 8i fathoms; off Ceylon, 

 Indian Ocean, 35 fathoms; Colombo Harbour, 7 

 fathoms; Suez (Egypt), and Port Said, 28 fathoms. 

 He also had some from .Aden, but said it putrified and 

 stunk his cabin out so he had to commit it to the deep 

 ag^ain. This officer is now in home waters, and has 

 offered verv kindlv to collect for me more material 

 when the opportunity occurs. The Adriatic anchor 

 mud, &c., with the exception of five, which I got my- 

 self, were sent me by an officer in the .Austrian Xavy, 

 and were taken from a torpedo-boat, on which he was 

 cruising-. One of them was actually taken from a dis- 

 charged and recovered torpedo, which should have had 

 a very g^ood sample as it would be running along the 

 bottom for some little distance when slowing down. 

 This officer I had interested very much when I was over 

 there last year, showing^ him with a pocket lens of 20 

 diameters the lovely little shells. He has also promised 

 to send me more when he has an opportunity. " I 

 wish I could reproduce more of Mr. Heath's very inter- 

 esting letters, which show how an enthusiastic collector 

 may enlist the help of others for his hobby. Those of 

 my readers who would like .some of this sand must 

 send me a stamped addressed envelope, a small tin box, 

 and the coupon to be found in the advertisement 

 columns of this issue. May I add that the number of 

 applicants is generally so great that I cannot pay any 

 attention to applications which do not carry out all of 

 these simple conditions. It would be amusing- were I 

 to detail some of my experiences in distributing material 

 of this nature. 



Notes and Queries. 



C. E. G. {f^hanijhai). — Vour Ittlir inler^■^tf■d me verv much, 

 and I feel sympathy for anyone working- under vour condi- 

 tions. I think you rannot do bftlcr than devote vour atten- 

 tion to mites, an<i I woidd refer you to an article on the 

 subject contributed by Mr. C. W'arburton to these columns, 

 and published in May and June, 1904. Mr. Warburton is 

 one of the authorities on the subject, and in his article tjives 

 notes as to collecting-, &c. If you decide to take up the 

 matter definitely I shall be glad to put you into communica- 

 tion with him, or with others who are likewise interested 

 in the subject. With regard to the photographs, yeast is 



ver\- difficult on account of its want of contrast, and I shall, 

 therefore, not be too critical about it. The others are good 

 attempts for a beginner, and their most serious fault is that 

 the slides themselves are not satisfacton,'. In making 

 mounts of insects you cannot be too painstaking in the 

 initial stag^es of preparation. If you begin by treating with 

 caustic potash, the whole process must be carefully watched, 

 and the turpentine stage must be equally closely watched, 

 but a section that is not transparent, or one that is not 

 uniform, is useless for photography. In the photograph of 

 the flea, for instance, the legs are so pale as to have no 

 contrast, whilst the bodv is almost opaque. A similar 

 criticism applies to the head of the mosquito, and to the 

 beetle's head. You have also a tendency to get an illu- 

 minated disc that is not quite uniform, which spoils the ap- 

 pearance of the photograph, the remedy being careful 

 centring^ and adjustment of all the optical arrangements, 

 especially the condensers, as laid down in my articles on 

 photo-micrography in this journal (November, 1905, to June, 

 1906). .Some of the photographs are not precisely focussed, 

 and in others there is a tendency to stop down the condenser 

 too much. Ordinan,' low-power objectives are not satisfac- 

 tor\- for photo-micrography, and it is well worth purchasing 

 one or more of the piano-lenses made by various opticians. 

 W. Watson and Sons make a good series under the name of 

 " Holostigmatic " at /^^ each, of which the most generally 

 useful are the 3-in. and 33-in. Reichert also makes a good 

 series, of which the most useful are a 3-in. at 50s. and a 

 4-in. at 60s. Zeiss' Micro-planars are excellent, but thev 

 cost ;C.6. -All these are used without eyepiece. Watson's 

 Variable Magnifier is unsuitable for photography, being de- 

 signed as a hand or dissecting lens. Achromatic lenses per- 

 form fairly well without eyepiece, but the image is 

 sharpened by using a projection ocular, the lower in power 

 the better. 



IF. M. H. (Winchester). — There are several methods of 

 reproducing drawings, whether from illustrations in books 

 or not, but the simplest way is to photograph them direct. 

 For this any ordinan,- photographic camera is suitable, pro- 

 vided it has a camera extension which will allow it to photo- 

 graph at quite a short distance. For my own work I use a 

 ^vS .Ss. |-plate " Kodak," which has a camera extension 

 which enables me to focus an illustration set up about 17 

 inches away, the lens being a good one and fairly flat in the 

 field. By a little ingenuity an ordinary- photographic lens 

 could be fitted for this purpose at the end of a photo-micro- 

 graphic camera. It is then only necessar\- to set the page 

 to be photographed opposite to the lens, making sure that it 

 is vertical, at right angles, and that the whole page is flat, 

 to illuminate it with as strong a light as possible, and to 

 photograph as usual. .A suitable wooden stand is easily 

 made. In making the negative it is important to get sharp 

 definition and a clean ground, any fogginess spoiling the 

 slide for lantern purposes. By using :J-plates it is easy to 

 print ordinary 31-inch square lantern slides by direct con- 

 tact with the negative thus m.ade, the two plates beinsj 

 printed in an ordinary frame, the lantern slide taking the 

 place of the ordinary printing paper, and exposed to litrht 

 in the same way. I have had excellent results with Ed- 

 wards' " Kristal " plates, full instructions for development, 

 &c., being sold with each packet. It is best to take the 

 negatives on a J-plate if possible, as otherwise thev have 

 to be reduced in size, which is a nuisance. I assume that 

 you are familiar with ordinary photographic methods, in 

 which case the above hints will, I hope, serve your purpose. 



Orran Ooze anil Diafomarrmis Earth. — Mr. G. E. O. 

 Mullins, of Bristol, will be grateful if any reader can tell him 

 where he can procure ocean ooze. He .says he has watcheil 

 the advertisements in the scientific journ.als for some time. 

 He would also be glad to know where he can obtain the 

 diatomaceous " mountain llour " of Norway. With regard 

 to the former inquiry, Mr. Mullins will probably read with 

 interest the rem.arks accompanying Mr. Heath's olTer of 

 dredgings from the .Adriatic in another part of these 

 columns. Mr. Heath very kindly offers to allow him to 

 select from the material mentioned. 



[Communications and inquiries on Microscopical matters should he 

 addressed to F. Shillinolon Scales. " Jirsey." St. Bamalyas Road. 

 Cambridge. Ccrresf>ondtHts are requested not to send specimens to be 

 named.] 



