1824.] Scientific Notices — Miscellaneous. 235 



times, was 2 feet 2 inches perpendicular in five minutes, and 

 again actually made a reflux of 3 feet 6 inches in the same short 

 space of time, tearing up the soil from the bottom of the river, 

 the agitated thick surface of which resembled the boiling of a 

 pot. The vessels at the Breakwater one minute were afloat, and 

 the next lying high and dry on the body of the works ; and but 

 for the great exertions of the workmen and crews, much damage 

 must have been done. Indeed, was there a possibility of lifting 

 that stupendous structure from its position only for an hour, not 

 a ship could have been safe either in Plymouth harbour or in 

 the Pool ! and although it must appear strange, at the same 

 time the sea in the offing was particularly smooth. About half- 

 past two, p. m. the tide began to resume its regular course. No 

 doubt we shall soon hear of some extraordinary convulsion of 

 nature in some part of the world. In 1798, a similar occurrence 

 took place, about the time of the dreadful earthquake in Sienna, 

 which swallowed up many thousands of our fellow creatures. — 

 (Plymouth Journal.) 



8. Unequal Distribution of Heat in the Prismatic Spectrum. 



That the different portions of the prismatic solar spectrum 

 possess different heating powers, has been universally admitted 

 by every philosopher who has examined the subject experiment- 

 ally ; but a great diversity of opinion has prevailed respecting 

 the precise point where this power resides in its greatest inten- 

 sity. Landriani, one of the first who investigated this subject, 

 placed the maximum heating power in the yellow rays, Rochon 

 in the orange or orange yellow, and Senebier also in the yellow. 

 Herschel, on the contrary, found the heating power of the red to 

 be superior to that of all the other coloured rays ; but that there 

 is a certain point of the spectrum, situated immediately beyond 

 the red and invisible, which elevates the thermometer still higher 

 than any of the visible rays. His experiments were directly 

 contradicted by Leslie, but were soon after in a great measure 

 confirmed by Englefield. Dr. Seebeck, in a memoir read to the 

 Royal Academy of Sciences in Berlin, which with numerous ori- 

 ginal experiments combines a copious discussion of the opinions 

 of preceding inquirers, appears to have ascertained the cause of 

 those anomalous statements. It exists in the particular nature 

 of the medium by which the rays of light are decomposed ; a 

 circumstance so little regarded that few experimenters have even 

 deemed it necessary to record the material of their prism. The 

 following is a summary of his results. 



In every part of the prismatic spectrum, there is a percepti- 

 ble elevation of temperature, and this is uniformly least in the 

 outermost edge of the violet. From the violet it gradually 

 increases, as we proceed through the blue and green, into the 

 yellow and red. In some prisms, it attains a maximum in the yel- 



