1828.] 



Varieties. 



93 



per, iron upon marble, and, by using -'the 

 balistic pendulum, by lead upon lead, and, 

 with suitable precautions, even by lead 

 upon wood. The experiments were suc- 

 cessful both with English and French pow- 

 der, and clearly show that in all the mani- 

 pulations of a powder manufactory, all 

 violent shocks and percussions should be 

 carefully avoided, since they may occasion 

 the disengagement of sufficient heat to 

 produce the inflammation of powder. 



Fluid Object Glass Telescopes. Messrs. 

 Gilberts have executed, under the direc- 

 tion of Professor Barlow, two telescopes, 

 with fluid object glasses. The smaller 

 "has an aperture of 3-25 inches, the larger 

 of 6 inches. The smaller glass, with a 

 power of 46 shews the star Polaris, distinct- 

 ly double, with the small star well defined ; 

 and with higher powers, all the double 

 stars of Sir W. Herschell's third class are 

 distinctly separated, and several of the 

 second class. In the larger class, a se- 

 condary spectrum is formed, which is 

 very obvious with light stars, as Lyrse 

 and Arcturus, but with smaller stars scarce- 

 ly perceptible. The inventor expects to 

 remove it by altering- the mixture of his 

 fluids. The tube is materially shortened, 

 by separating the fluid glass lens, by a 

 considerable interval, from the exterior 

 lens of crown glass. The principje is said 

 to be different from that of the late Dr. 

 Blair, whose son is still actively engaged 

 in giving effect to his father's discovery. 

 He has object glasses of Dr. Blair's con- 

 struction, in which the fluid has been now 

 enclosed the long space of twenty-one 

 years, without suffering the slightest al- 

 teration. The telescope on which Mr. 

 Blair is at present employed, will have 

 5$ inches aperture, and 5 feet focal length. 



Fossil Bones. In a cavern in the com- 

 mune of Lunel-Viel, recently explored, 

 there have been found the bones o twenty- 

 one recognized species, imbedded in a 

 fresh water alluvium ; they are heaped 

 together in a confused manner, sometimes 

 entire, often broken and mutilated, but 

 never worn or rounded they include two 

 varieties of the hyena, the lion, bear, 

 rhinoceros, horse, deer, ox, shark, and 

 sea tortoise. Professor Buckland, on 

 visiting the cavern ofOiselles, near Be- 

 sanfon, which was an object of curiosity 

 from the brilliancy of its stalactites, ob- 

 served that it had all the appearances of 

 the caverns of bones in Franconia, he was 

 therefore led to examine the soil, and 

 found his conjecture verified. On further 

 investigation it has been found to contain 

 as surprising a quantity of bones as the 

 caves of Franconia ; but it is remarkable 

 that these bones, without exception, be- 

 long to the ursus spelaeus. 



Barometrical Reductions. Various 

 tables have been published by different 



authors, to reduce observations of the 

 barometer to a standard temperature, the 

 following method appears easy and sim- 

 ple : The expansion of mercury from 32 



to 212 is, according to De Luc g^ La- 

 voisier and La Place, 1 Hallstrom. 



55-22 



Dulong and Petit, the mean of 

 55 5<r5 



these is this 



5543 



Fahrenheit's scale = 



for each degree of 



9977-4 

 which does not differ sensibly fror 



00010023 



1 



10-00 



if then before the first three figures o f 

 the observed height we place two cyphers* 

 and multiply by the excess or defect of the 

 temperature from 32 the product sub- 

 stracted or added to the observed height 

 will give the required reduction. For 

 example, let the observed height of the 

 barometer be 30-597, and the temperature 

 of the mercury 74 -00306 + 7432 = 

 129 and 30-597 129 = 30 468 the cor- 

 rected height. 



Professor Airey^s left Eye. Some two 

 or three years ago, Mr. Airey accidentally 

 discovered that his left eye was totally 

 useless; some considerable time after- 

 wards, he made the further discovery that 

 there was something peculiar in the re- 

 fraction of that eye. By a mathematician 

 and philosopher of less pretensions than 

 Mr. Airey this might have been unheeded 5 

 but as new lights are now a la mode, he 

 followed it up by instituting a course of ap- 

 posite experi ments on the defective eye, and 

 ascertained that it had a different refrac- 

 tive focus in two planes at right angles to 

 each other. He, in consequence, procured 

 a double concave lens, with one surface 

 spherical, the other cylindrical, having 

 previously calculated the radii which 

 would be required ; and we have the satis- 

 faction of learning that the defective eye 

 can now be used in almost every respect 

 as well as the other, in fact, like many 

 other sons of alma mater, he is now 

 enabled to see double ; but the above ex- 

 planation may serve to account for a cer- 

 tain obliquity of vision we bad occasion to 

 remark a few months ago. 



Remarkable Hybrid. A correspondent 

 of M. de Freussac has advertised him of 

 the production, at Berlin, of an animal 

 between a stag and a mare the appear- 

 ance of the creature is very singular, the 

 fore part being that of a horse, the hinder 

 part that of a stag, but all the feet like 

 those of the latter animal. From the inti- 

 macy of the same stag with another mare, 

 a second specimen is confidently antici- 

 pated. 



