Notes and Memoranda. 309 



miles high, even of a delicate nature, can be made as completely in 

 the balloon as on the earth ; that at heights exceeding' four miles 

 they cannot be made quite so well, because of the personal distress 

 of the observer ; that at five miles high it requires the exercise of a 

 strong will to make them at all ; that up to three miles high any 

 person may go into the car of a balloon who has any ordinary degree 

 of self-possession ; that no one with heart disease or pulmonary 

 complaints should attempt four miles high. 



NOTES AND MEMOBANDA. 



The Distorted Skulls of Wroxeter. — Dr. Henry Johnson, of Shrewsbury, 

 communicates to the Royal Society an explanation of the deformity exhibited by 

 nine and twenty skulls discovered at Wroxeter. He ascertained that the sod in 

 which they were foimd was acid, and then made an experiment by keeping a piece 

 of fresh bone for a month in water impregnated with carbonic acid, which was 

 found to be flexible at the end of that time. He therefore concludes that the 

 deformity of the skulls was not congenital, but posthumous, and occasioned by a 

 softening of the bones soon after interment, and the pressure of the super- 

 incumbent sod. After the animal matter of a bone has disappeared, it would 

 break, not bend. 



The Photographic Transparency of Bodies. — Professor W. Allen Miller 

 has laid before the Royal Society a valuable paper on this and an allied subject, 

 " The Photographic Effects of Metallic Spectra, obtained by means of the Electric 

 Spark." He finds that " colourless bodies which are eqtialfy transparent to the 

 visible rays, vary greatly in permeability to the chemical rays ;" that " bodies 

 which are photographically transparent in the solid form preserve their trans- 

 parency in the liquid and in the gaseous states," and that colourless transparent 

 solids, which exert a considerable photographic absorption, preserve their absorptive 

 action with greater or less intensity, both in the liquid and gaseous states." Glass 

 vessels could not be employed in these experiments, " as they all, even in thin 

 layers, shorten the spectrum by from three-fifths to four-fifths, or even more, of 

 its length." Rock crystal, cut in thin slices and polished, was the only substance 

 the Professor found he could use with advantage. After atmospheric air and 

 certain gases, rock crystal, ice, pure water, and fluor spar are most perfectly diactinic, 

 and rock salt is scarcely, if at all, inferior to them. Among the salts of inorganic 

 acids, the nitrates are the most remarkable for their power of arresting the che- 

 mical rays. Most liquids, except water, arrest more or less of their rays, and they 

 are stopped by trichloride and oxychloride of phosphorus, although perfectly 

 transparent and limpid. Reflection from a metallic speculum caused a great loss of 

 actinic power. 



The Long- Spectrum op Electric Light. — In 1853 Professor Stokes exhi- 

 bited this spectrum at the Royal Institution, using electric light. He had pre- 

 viously found that glass was opaque for the more refrangible and invisible rays of 

 the solar spectrum, and that electric light contained rays of still higher refraii- 

 gibility. Rejecting the glass, and using a prism and lens of quartz, he obtained a 

 spectrum which, when thrown upon a highly fluorescent substance, was found to 

 be six or eight times as long as the ordinary spectrum. He has recently laid 

 further researches before the Royal Society, and among the metals he has examined 

 he finds aluminium capable of producing the largest number of rays of extreme 

 refrangibility. "With some metals, broad and hghtly convex electrodes exhibited 

 the invisible lines better than wires, and the Professor adds : " The blue negative 

 light formed when the jar is removed, and the electrodes are close together, was 

 found to be exceedingly rich in invisible rays, especially invisible rays of moderate 



