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HARDWICKE'S SCIENCE-GOSSIP. 



at the bottom. I am told such a thing has often 

 been inquired for ; and as I have at last succeeded 

 in making a very simple yet effective plummet, I 

 thought a description of it would interest your 

 readers. The sketch will illustrate it better than a 

 mere written description could. The body a is a 

 tube, made of tinned iron or copper, with a lid 

 at top, furnished with bayonet catches, to prevent 

 it coming off. At the bottom a conical piece of 

 tin, b, with the top of the cone cut off at c, is in- 

 serted and soldered to the tube. A ball (I find 

 a common indiarubber ball, such as are sold for 



"W 



^ 



A 



Fig. 72. Sounding Apparatus, with section of same. 



children to play with, acts very well, and the cost 

 is only about threepence each), nearly the same 

 diameter as the tube, works freely inside it, and 

 falling on. the seating at c, makes a joint. A lead 

 ring e slips on the tube, and rests on the ledge at f. 

 When in use, the sounding-line is fixed to the 

 handle at the top, and the boat being stopped, or 

 nearly stopped, the plummet is let go. On touching 

 the bottom, it should be slightly lifted, and let 

 down gently, to insure it resting right side up. 

 The weight of the lead ring will force the bottom 

 part of the plummet into the mud or sand, which 

 will be forced up inside, lifting the ball r>, and 

 flowing through the opening c into the trough G ; 

 on raising the plummet, the ball immediately falls 

 back on its seating, aud the contents of the plummet 

 are brought to the top. I tried it last summer, and 

 never failed to bring up a good specimen, sufficient 



to find a good many hours' work with the microscope, 

 and the most delicate Foraminifera, Diatoms, and 

 Entomostraca were not only perfect, but alive. My 

 plummet is about eight inches high, four and a 

 quarter inches diameter outside the lead ring, and 

 weighs about nine pounds. It can be made for a 

 mere trifle by any tinman ; or it can be purchased 

 from Mr. Highly,* to whom I have shown the idea, 

 and who lias undertaken to make them for sale. 

 Of course, for very great depths, the indiarubber 

 ball would have to be weighted a little, as it is 

 obliged to be of slightly greater specific gravity 

 than the water. I venture to hope that this little 

 " dodge " may induce some to enter upon a study 

 yet in its infancy, and, by enabling even amateurs 

 with not very well-lined purses to study the minute 

 forms of life found at the bottom of the sea around 

 our coasts while living, may add something to our' 

 stock of knowledge. Since writing the above, 

 Science-Gossip for this month has come to hand, 

 and one of your correspondents has tried to help 

 me out of last year's difficulty. While thanking him 

 for his good intentions, I fear he has little idea of 

 the practical difficulties of the question. If he had 

 to draw his plummet through thirty or forty fathoms 

 of water, he would not find many organic substances 

 in the holes, even if heavy grains of sand would 

 stay in, which I doubt. My aim was to get some- 

 thing so simple, that it could be worked even on a 

 tolerably rough sea, and yet so certain, that the 

 labour of lifting a heavy plummet through the water 

 would not be labour lost. — C. L. Jackson. 



Spring A 7 isitoks.— Swallow, April 23rd ; Corn- 

 crake and Cuckoo, 24th; Blackcap, 26th. The weather 

 very unfavourable at the time, and continued extra 

 cold for several days after their arrival. Yet, not- 

 withstanding all this, their appearance this year is 

 a few days sooner than usual. — John Sim, West 

 Crahilington, Northumberland. 



In t sect Catalogues. — In reply to numerous 

 inquiries for catalogues of insects, we are enabled to 

 state that some copies may still be obtained of 

 Waterhouse's Catalogue of British Coleoptera. Also 

 that a new catalogue of British Coleoptera is in 

 active preparation, and may soon be had of 

 Mr. E. W. Janson, No. 28, Museum Street, 

 London, from whom may be obtained Marseul's 

 Catalogue of European Coleoptera at one shilling 

 (well worth the money), and T. A. Marshall's Cata- 

 logue of British Ichucumonidse. We have already 

 alluded to Mr. McLaehlan's excellent Catalogue of 

 British Neuroptera, and Dr. Knaggs's Catalogue 

 of British Lepidoptera. We are informed that all 

 these lists are still on sale, and may be had of 

 Mr. Janson. 



* 1»a, Great Portland- street, London. 



