332 ANNUAL OF SCIENTIFIC DISCOVERT. 



particularly through the observation of Humboldt, that the barometer 

 rises and falls during the day in a peculiar manner ; being at its max- 

 imum height at 10 A. M. and at 10 p. M., whilst the lowest readings 

 are between 4 p. M. and 4 A. M. The regularity of this periodical 

 movement within the tropics is such, during the year, that Humboldt 

 could tell the time within fifteen minutes. This movement has been 

 observed with much regularity in Santiago de Chili during the win- 

 ter and summer months ; but in the month of February the movement 

 entirely ceases, showing then only the extraordinary maximum and 

 minimum heights in the twenty-four hours. 



Senor Moesta has tried to explain this occurrence, and has demon- 

 strated mathemetically that the oscillatory movement of the barometer 

 is produced by the sun's power, analogous to that of gravitation, and 

 that the said movement ought to disappear in the month of February, 

 in consequence of the great variation of temperature during the course 

 of the day. Thus the interesting rqult has been arrived at, that, by 

 virtue of the sun's power, a movement is manifested in the atmosphere 

 analogous to the action of the tides ; and it is this that causes the rise 

 and fall of the barometrical column in Santiago, about " 1.3 of a mil- 

 limetre." Comercio de Lima, 8 January, 1863. 



FORMATION OF HAIL. 



M. Sanna-Solaro contests the idea that hail-stones are formed by 

 successive concretions. On the contrary, he affirms the congelation to 

 begin from without, and the so-called nucleus to be the result of pres- 

 sure. He says that when the external surface begins to freeze, the 

 air bubbles are driven toward the centre, and give rise to a pressure 

 under which the crust yields, " The shock determines the congelation 

 of a fresh layer, which is formed of two distinct parts, one deprived of 

 air and transparent, the other opaque, in consequence of its included 

 air-bubbles." This phenomenon is reproduced at each successive con- 

 gelation, and if the hail-stones reach the ground before the congelation 

 is complete, their central portion may contain bubbles of air, water, 

 and crystals of ice. Pyramidal stones he ascribes to the action of vio- 

 lent congelation, which causes the contained fluid to split the crust. 

 He states that he has imitated hail-stones by freezing water in trans- 

 parent envelopes of caoutchouc. He likewise adduces reasons, to show 

 that hail-stones are formed instantaneously. Further details will be 

 found in Comptes Rendus, 27th April, 1863. 



LIFE IN THE ATMOSPHERE. 



The following is an abstract of a paper on the above subject, present- 

 ed to the British Association, 1863, by Mr. J. Samuelson. No subject 

 in natural history except the allied one, the origin of species, had of 

 late excited greater interest in the scientific world than the origin of 

 the lowest types of living beings on the globe ; and although the prob- 

 lem was far from being solved, yet, the investigations that had accom- 

 panied the discussion had already served the useful purpose of throw- 

 ing new light on the anatomy and life history of the mysterious little 

 forms of which it treated. It was rather with the latter object, than 

 in the expectation of being able to assist in the solution of the general 

 question, that he ventured to lay before 'the Association the results of 



