68 Notes and Memoranda. 



carry out the munificent intention of Mr. Gassiot, who gave the order for its con- 

 struction, for the purpose of placing the finest possible means of spectroscope 

 inquiry at the disposal of the cultivators of this branch of science. The instru- 

 ment is furnished with nine exquisitely-finished prisms, possessing in the aggre- 

 gate a very high dispersive power. The telescopes attached to it are two feet 

 long, supplied with numerous eye-pieces and every appliance to facilitate delicate 

 and difficult investigations. For any ordinary purpose, a less costly and compli- 

 cated spectroscope is amply sufficient, and the famous researches of Kirchhoff and 

 Biinsen were made with very inferior means. In able hands we cannot doubt 

 that the G-assiot spectroscope will add an important chapter to the revelations of 

 light, and it must be regarded as a noble instance of judicious generosity on the 

 part of an esteemed and successful cultivator of physical science, and of exquisite 

 skill as an optician on the part of Mr. Browning, to whom the credit of the con- 

 struction is entirely due. 



The Patent Achromatic Binocular Magnifier. — Having received from 

 Messrs. Smith, Beck, and Beck a case of the instruments described under this 

 lengthy title, and having employed them for many purposes, we can testify to 

 their great superiority over the simple lenses they are intended to replace. They 

 are composed of an achromatic combination on the binocular principle, but the 

 lenses are so cut that the effect is like employing the centre only of an ordi- 

 nary lens, and the angle is so arranged that the eye looks naturally through 

 them, without any of the squinting or straining which makes ordinary magnifiers 

 fatiguing and unsatisfactory. They arc of three sizes, having focal lengths of 

 seven, five, and three inches respectively, and can be used as hand magnifiers, 

 attached to a neat handle, or mounted upon a noveland ingeniously-devised stand, 

 which possesses a multiplicity of motions, and enables a very accurate adjustment 

 to be made. We have tried them for viewing photographs, for microscopic dis- 

 section, and for looking into bottles and aquaria, and in each case have had reason 

 to be satisfied with the facility and accuracy of their performance. 



Structure op Blood Corpuscles. — Dr. William Roberts, of Manchester, 

 has communicated to the Royal Society an account of experiments with human 

 blood corpuscles, and those of other vertebrate animals. The reagents he employed 

 were a solution of nitrate of rosanilin (magenta), prepared by making a nearly 

 saturated solution by boiling the salt in water, filtering after twenty-four hours, 

 and then slightly diluting it, and a solution of tannin, three grains to the ounce of 

 water. A speck of human blood was mixed with a drop of the magenta solution 

 on a glass slide ; the corpuscles became transparent, and of a faint rose colour ; 

 they expanded sensibly, lost their bi-concave figure, and a dark red spot made its 

 appearance on some portion of their periphery. When the blood of the oviparous 

 vertebrates was employed, the central nucleus came fully into view, and assumed 

 a deep blood-red colour ; the oval form of the corpuscles was lost, and a dark-red spot 

 appeared on their periphery. Tannin caused the corpuscles to bud or pullulate ; 

 one drop of blood mixed in a conical glass, with four or five of the solution, 

 generally answered perfectly. The pullulations were easily seen under the 

 microscope, by placing a drop of the tannin solution beneath the covering glass, 

 and permitting a little blood to insinuate itself under it. The pullulations 

 appeared organically connected with the corpuscles, but to form no part of their 

 cavity. Dr. Roberts concludes from his researches that the mammalian corpuscles 

 are homologous, as wholes, with those of the ovipara, and not with its nucleus, as 

 supposed by Wharton Jones; and that (ho envelope of the blood disk is a dupli- 

 cate membrane ; in other words, that within the outer covering there exists an 

 interior vesicle, which encloses the coloured contents, and in the ovipara the 

 Dtudetlf. JIo observes that Dr. Hensen, of Kiel, had attributed this structure to 

 the blood corpuscles of the frog, and that in this view the blood corpuscle is 

 anatomically analogous to a vegetable coll, and the inner vessel corresponds to the 

 primodial utricle. Further details will be found in Proceedings of the Royal 

 Society, No. 55. 



