Notes and Memoranda. 323 



NOTES AND MEMORANDA. 



Stab Finder. — Messrs. Home and Tliomtliwaite have supplied a want widely 

 felt by the possessors of telescopes, in producing a small, portable, and elegant 

 instrument, by which celestial objects may be easdy found from the data given in 

 the Nautical Almanack, or any similar authority. It is, in fact, a miniature 

 equatorial of accurate workmanship and very moderate price. We regret that the 

 demands upon our space oblige us to postpone any detailed description, but it is 

 due to our astronomical readers to give them the earliest intimation of a new and 

 important aid to their favom'ite pursuit. 



Taranaki Steel. — We have received from Messrs. Moseley a specimen of that 

 very curious and interesting mineral, the iron-sand from New Zealand, which 

 appears to realize all the expectations which were formed of its value in metal- 

 lurgy. The chemical composition of this ore, for such it must be called, is emi- 

 nently favourable for the production of the finer kinds of steel, as it not only 

 contains no element of a deteriorating quality, but has the great advantage of 

 possessing a considerable quantity of titanium. In appearance the Taranaki sand 

 resembles bright grains of gunpowder, and is readily attracted by the magnet. 

 Professor Herapath says it contains 16 per cent, of titanium, 6 of silica, and a 

 trace of manganese. The deposit extends for miles on the beach, at the foot of 

 the volcanic mountain Egmont, and when smelted yields 60 per cent, of iron of 

 the first quality. Under the microscope it presents a beautiful appearance, the 

 grains exhibiting very irregular but polished surfaces, with a lustre between that 

 of steel and silver. Here and there a grain will be observed, composed chiefly of 

 silica, dotted with minute portions of the ore, but it is singularly free from im- 

 purities. The steel made from it is highly praised, and when we remember the 

 extraordinary affinity of titanium for nitrogen at high temperatures, we call to 

 mind the recent assertion of a French chemist on the action of the last-named 

 element in changing iron into steel. 



Links between Feathers and Scales. — Mr. Latham exhibited to the same 

 society scales from the wing of the Catarrhactes papua, a penguin from the Falk- 

 land Isles. They appear intermediate between feathers and scales. This fact 

 should be considered in connection with the discovery of the feathered reptile in 

 the Solenhofen state. 



The Mass oe Jupiter. — M. Schubert expects to be able to calculate the exact 

 mass of Jupiter from the disturbances he produces on the asteroid Leucothea. 



Astronomical Photographs. — The beautiful photographs of M. Warren de 

 la Rue are a most valuable contribution to astronomical science. By means of his 

 labours we are obtaining a continuous history of the changes in the spots and 

 faculje on the face of the sun, more accurate and more instructive than could be 

 preserved by any verbal description or ordinary drawing. By this means questions 

 relating to the periodicity of these changes and their connection with terrestrial 

 magnetism will be solved, and likewise those concerning the movements of the sup- 

 posed ring of asteroids in the region of Mercury. Among the most remarkable of 

 Mr. de la Rue's works are stereoscopic views of the larger planets. As it would 

 be impossible to stereoscope objects so remote by the usual methods of operation, 

 he has obtained the requisite change in the aspect of the two views by photo- 

 graphing the planetary disks in two positions at two different periods of observation. 



The Sodium Spectrum. — Mr. Fizeau called the attention of the French 

 Academy, on the 3rd March, to the character of the light obtained by burning the 

 metal sodium in common air, when examined with the spectroscope. He ob- 

 served, " the results differed entirely from those obtained with other flames in 

 which the presence of sodium is revealed in a very constant manner by a yellow 

 light, which, when observed in the spectrum, presents the double ray D detached 

 from the background and very luminous. The effects produced with the burninp- 

 sodium do not coincide with the expectation of a great development of the ray D, 

 and we find with surprise that the spectrum it produces is continued after the red 

 as far as the violet, with the exception of the double ray D, which detaches itself 

 in shaded black (noir fonce) and like velvet on the brilliant ground of the spec- 

 trum. This appearance is the converse of that which is given by other flame's 

 containing sodium. With them, in fact, all the rays of the spectrum are wanting 

 with the exception of that which forms the ray D. With burning sodium all the 

 rays are very brilliant except those of the ray D, which appear entirely absent. 



