338 SCIENTIFIC RECORD FOR 1884. 



and, among other conclusions, he shows that for Paris we cannot safely 

 assume that the mean pressure in winter must be higher than in sum- 

 mer, as many years show the opposite condition. {Z. 0. O. If., xix, 

 p. 541.) 



273. Mr. H. F. Blanfordand Mr. Hill have published contributions to 

 the daily periodicity of the barometric pressure in India. The obser- 

 vations at Goalpara, Patua, Leh, and Allahabad have been especially 

 studied by them. In general it may be noted that the daily change of 

 pressure is in the valleys of the warm zone characterized by an early 

 occurrence oT the morning maximum. The daily amplitude is 0.0048 

 of the mean daily pressure, or about 0.14 of an inch. {Z. 0. G. M., xvii, 

 p. 258.) 



274. Prof. H. Mohn has published the volume containing the results 

 of the Norwegian I^Torth Atlantic expeditions, 1876 to J 878, in which he 

 contributes the first observations that we have of the daily periodicity 

 of meteorological phenomena in this important region of the North Sea. 

 With regard to the pressure, we have a scarcely perceptible minimum 

 between 8 and 9 p. m., a priucii^al minimum at 4 a. m., and a principal 

 maximum at 2 p. m. Combining this with the results of the Challenger 

 expedition it seems likely that there is no evening minimum under nor- 

 mal conditions in this region ; so that on the open sea in high latitudes 

 in both North and South Atlantic only one miniaium and one maximum 

 appears in the diurnal curve of pressure. {Z. 0. G. M., xviil, p. 470.) 



275. J. M. Pernter contributes to the subject of daily and annual 

 variations of pressure on mountains and in valleys a short study of 

 some observations in Austria, Switzerland, and on Mount Ararat. He 

 finds the following results for mountain peaks: 



1. The curve of daily change is flatter for the elevated stations, the 

 morning minimum diminishes, while the afternoon minimum grows flat- 

 ter, but without disappearing, as it is still very prominent upon Mount 

 Ararat ; up to a moderate height the daily amplitude diminishes, but 

 then begins again to increase. 



2. The evening maximum, that is quite small in low, flat lands, in- 

 creases with the altitude until it finally becomes the principal maximum 

 of the day. This has been known in a few instances, and ascribed to 

 special local circumstances, but is now recognized as a general law of 

 much import. 



3. The periodicity during the day is not the same for summer and 

 winter seasons : thus for a low peak in summer the mid-day maximum 

 comes later than in winter, and this delay is greater in j)roportion to 

 the altitude, amounting to two hours at the highest station. 



With reference to valley stations, he finds a dearth of material in the 

 higher Alpine valleys, but comes to the following co:iclusions : 



4. The daily amplitudes are remarkably large. 



5. The afternoon minimum is remarkably deep. 



