356 



♦ KNOWLEDGE ♦ 



JoNE 15, 1883. 



be seen in activity on Mr. Bolton's table at stand 75G, 

 beyond the aquarium. 



The question may now bo asked, Is Amwba a permanent 

 type 1 Assuredly so ; but it very often is only a phase in 

 the life-history of some higher form— e.//., the well-known 

 fresh-water polype (/fi/ilra), whoso fertilised ovum escapes 

 in tlie shape of A mo ha. In this connection there are a 

 large number of problems which yet remain unsolved, and 

 are of great interest, not only to the scientific investigator, 

 but also to those who are concerned with the economies of 

 fish and fishing. It has been stated that the spat of 

 oysters are very often preyed upon by Ainobc, which have 

 been found in large numbers amongst the decaying fish 

 of the culture beds. If this is in reality the case, some 

 attempt should be made to destroy the Aviw//cv; from 

 analogy, however, we are inclined to suppose that the effect 

 has here been confounded with the cause, and that the 

 A maid' result from pre-e.\isting germs which find a suitable 

 nursery in the already dead spat. It would, we believe, 

 be as wise to attribute the death of a cat to the larva; of 

 the blowfly which are invariably associated with its car- 

 cass ; and we are further supported in our conclusion by 

 the fact that the best hunting-grounds for Amabo'. are 

 ponds in which dead cats and dogs abound. Our simple 

 experiment for the manufacture of Protommha, too, is 

 another circumstance in favour of the view that some 

 Ami'ba:, at all events, are produced from germs which 

 derive their pabulum from decaying animal matter in the 

 presence of water, light, heat, and vegetable growths. 



The presence of Anudia and kindred forms, such 

 as the remarkable Protomyxa; of Hsccckel, in enormous 

 numbers in the depths of the sea and in fresh water, 

 render it highly probable that these organisms furnish fish 

 of all kinds with an important part of their food. Evidence 

 is not wanting to show that the minute testaceous Fora- 

 minifera (the group among which Amoba is classed) are by 

 no means despised by even such large fish as the cod, 

 whose stomach is often quite a museum of rare and beau- 

 tiful forms. We propose, in continuation of this, to fui-- 

 nLsh our readers with a few pencil sketches of these exqui- 

 site organisms, and to link together the manifold variations 

 in their existence which have resulted in phenomena — truly 

 stupendous. 



{To he continued.) 



TuE Scientific American gives some facts relating to the 

 manufacture of fiddle-strings, and says : — "The name ' cat- 

 gut,' as applied to the animal fibre strings, is altogether a 

 misnomer. The cat is in nowise responsible for the string, 

 and, much as the fact is to be deplored, the manufacturers 

 of such strings refuse to utilise cats for the supply of their 

 material. That disposes of the last excuse for the existence 

 of the cat. Catgut is of no use to anybody but the cat ; 

 hence no consideration of damage to valuable raw material 

 need hereafter stay the hand that hurls the avenging boot- 

 jack at the nocturnal serenader on the back fence. Violin 

 strings, and all sorts that come under the general head of 

 ' gut,' are made from the entrails of lambs and cattle, from 

 the delicate threads used for sewing racket-ball coyers up 

 to the half-inch thick round belts. After the lamb is seven 

 months old its entrails are no longer fit for making strings 

 for violins ; consequently this branch of the manufacture 

 can only be carried on a few months in each year. The 

 only man who now carries it on in America says that he 

 cannot, without tariff protection, compete with the cheap 

 labour of Germany and France, and he is going to give 

 it up." 



A GREAT TELESCOPE.* 



"1^7"^ have seen the wonders of the starlit sky through 

 Vt the largest and best refracting telescope in the 

 world ; but the wonderful instrument is not destined to 

 remain in America. The most important part of it, 

 the object glass, with the cell that holds it in place, will 

 soon be on its way to the Russian Observatory of Pulkowa, 

 located on the Pulkowa Hills, nine miles south of St 

 Petersburg, and commanding a fine view of the capital. 

 The Observatory was built and richly endowed by the Czar 

 Nicholas in 1839, and has won high renown on astrono- 

 mical annals for the work it has already accomplished 

 under its first director, the eminent astronomer Wilhelm 

 Struve, as well as imder his son, Otto Struve, who became 

 director in 1864, upon the death of his distinguished father, 

 and still holds the honourable position. 



The Russian Government was not satisfied with the 

 capacity and size of the present working force of the Ob- 

 servatory, and determined to have a new refracting tele- 

 scope constructed which, in mechanism and optic power, 

 should surpass any telescope in existence. The director 

 (Struve) was commissioned to carry out the plan. The 

 most perfect workmanship attainable was to be put in 

 requisition, and Struve chose from all the world, for the 

 execution of the difficult and delicate task, the Messra 

 Alvan Clark i Sons, the famous telescope-makers of Cam- 

 bridgeport, Mass. 



Struve came to this country and intrusted to their skilful 

 hands the making of the object-glass, with a diameter of 

 thirty inches, ' and its cell. The mounting of the great 

 telescope is being made in Hamburg, Germany, by Messrs. 

 Repsold ife Sons. The Pulkowa object-glass is four inches 

 larger than that of the Washington telescope, finished in 

 1873, and seven inches larger than that of the similar 

 instrument recently completed for the Princeton Observa- 

 tory, both telescopes being the work of the same makers. 

 The arrangements with Messrs. Clark were made in the 

 summer of 1881, and the great objective was completed in 

 October, 1882. 



A temporary equatorial stand was erected in the yard 

 of the workshop, in order to test the quality, power, and 

 perfection of the glass. It consists of a pier of solid 

 masonry, to which a tube of sheet-iron, made in three sec- 

 tions, is firmly fixed, with the necessary mounting to secure 

 its movement in the required direction. The object-glass, 

 the eye-pieces, and other appurtenances being then placed 

 in position, the great" refractor was ready to show its 

 working power, and to reveal any slight imperfections in 

 the polish or finisli that required attention. The precious 

 glass bore the testing process with triumphant success, and 

 is pronounced by the makers to be the best that has left 

 their hands. 



But the supremacy of the Russian telescope as the 

 largest of its kind in the world will be of short duration. 

 The same trial mounting will be used by the Messrs. Clark 

 for testing the 36-in. object-glass which they have engaged 

 to make for the Lick Observatory of Califoraia. 



The pier of the temporary structure is 27 ft in height ; 

 the tube is 4.5 ft. in length, with an aperture of 40 in. in 

 diameter. Figm-es, however, give a faint idea of this giant 

 structure. It must be seen looming up under the sky 

 before its huge dimensions can be realised. A view of the 

 heavens through its great eye must be taken before its 

 wondrous light-gathering power can be imagined. 



The evening of our observation is intensely cold, but the 

 sky is undimmed by the shadow ] of a cloud, the atmo- 

 sphere is free from a breath of moisture. The heavens 



* From the Scientific American. 



