104 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



to be the result of variations of the temperature, seems to be 

 without foundation. Broun, therefore, states that he has es- 

 tablished two facts, which must be known and understood 

 before one can propose any hypothesis which shall explain 

 the daily variation of the barometer. The first relates to the 

 change in the daily variation with the season, and may be 

 stated, in brief, as follows : That the barometric variation 

 during the day-time, in the summer, resembles that which is 

 produced in the night-time in the winter, and vice versa. 

 This fact Broun has established for Makerstoun, while Lloyd 

 has equally established it for Dublin, and Quetelet for Brus- 

 sels. The second fact alluded to by Broun relates to the 

 change of the daily variation with the altitude above the sea. 

 This change seems due to an entirely different cause from 

 the variations of temperature. By comparing a number of 

 stations in India at various heights, varying from the sea 

 level to 6000 feet, it appears that the hourly variation ap- 

 proaches a constant value as w^e approach regions of constant 

 atmospheric conditions. Up to the height of 6000 feet, the 

 semidiurnal oscillations are proportional to the average 

 pressure. These two facts taken together lead Broun to the 

 belief that the semidiurnal oscillation, and the diminution of 

 its amplitude as we rise in the atmosphere, accord with the 

 hypothesis that both result from a polar attraction of the 

 sun, producing an attraction on one side of the earth and a 

 repulsion on the opposite side. 6^, 1873, 1536. 



THE UPPER CURRENTS OF AIR. 



The interest excited on all sides by the persistence of 

 Professor Wise and the editors of the Qraphic in the bal- 

 loon voyage which came to such an untimely end, has 

 done good service to meteorology, so far as it has called 

 forth an expression of opinion from almost every one whose 

 opinion has been worth having. Among those who have 

 communicated their views to the editon-s of the Graphic., 

 nothing has appeared more decisive of the point, and at the 

 same time more interesting, because of the novelty of the 

 observations, than the communication from Professor IT. A. 

 Newton, of Yale College. He writes that he has observed, 

 with great care, the bright trains sometimes left behind in 

 the upper air by the shooting meteors. They afford, as is 



