148 



NATURE 



[February io, 1898 



The theoretical value is that given by the assumed 

 formula, 



g^ = 978 066 (I + 0-005243 sin- latitude), 



and g^ is obtained by using Bouguer's formula. 



It would not be easy to over-estimate the value of these 

 accurate determinations of gravity, for they help to fill a 

 very serious gap in the series of observations which have 

 been made in various parts of the world. Prof. Helmert's 

 recent report to the International Geodetic Association 

 has shown that no pendulum observations had been ob- 

 tained in the region visited by Mr. Putnam, and it is in 

 the polar regions that data as to the variations of gravity 

 are of the greatest importance and, therefore, most 

 urgently required. Mr. Putnam concludes his report 

 with some historical notes on the development of ap- 

 paratus and the progress of research, which are very in- 

 teresting. It is hardly correct, however, to say that the 



law t — TT A / - applies even to the ideal simple pendulum 



(p. no). These notes contam a good account of the 



controversy which has arisen about the appropriateness 



of the second term in Bouguer's formula for the reduction 



2P-H / 3S \ , , . , 

 of g to sea level : clq — ^ t i - ^ J, where o is density 



of matter lying above sea level, and A is the mean density 

 of the earth. The value of pendulum observations as 

 affording indications of surface density is insisted upon, 

 and a practical application of the method is suggested. 

 It is to be hoped that Mr. Putnam will see his project 

 realised, by which the relative proportions of ice and 

 rock in the great Greenland elevation may be determined 

 by" pendulum experiments. 



RAINFALL OF THE UNITED STATES. 



UNDER this title the Weather Bureau of the Depart- 

 ment of Agriculture has published a bulletin con- 

 taining a discussion of the observations obtained from 

 the longest and most trustworthy rainfall registers in the 

 United States, accompanied by annual, seasonal, and 

 other charts. In addition to the usual tables of the mean 

 monthly and annual precipitation, arranged according to 

 geographical distribution, an important departure has 

 been made by separately discussing the rainfall of the 

 crop-growing season ; for, as the author remarks, however 

 valuable a knowledge of the water supply throughout the 

 year may be, information as to the amount of rainfall 

 available for agricultural purposes is possibly of greater 

 consequence. 



Another departure from the ordinary treatment of the 

 subject is the discussion of the monthly distribution by 

 ■districts and types according to natural boundaries. The 

 conditions favourable for rainfall are chiefly (i) nearness 

 to the ocean, (2) proximity to the track of storms, and (3) 

 the position of mountain ranges. The rainfall of the North 

 Pacific coast is quoted as an example of the combined 

 effect of all three conditions, the distinguishing character- 

 istic of this type being a wet season from October to 

 March, and a practically rainless summer, except in 

 Northern California and parts of Oregon and Washington. 

 About half of the yearly fall occurs between December 

 and February. The rainfall is discussed under twelve 

 such types ; we are unable to refer specially to each of 

 these, but the chart of mean annual precipitation shows 



NO. 1476, VOL. 57] 



that there is a narrow belt on the north-west coast, ex- 

 tending from Cape Flattery on the north to midway of 

 the Oregon coast on the south, and some distance inland, 

 where the annual amount exceeds 50 and at some points 

 100 inches. Eastward and southward the annual fall 

 diminishes, reaching a minimum on the lowlands and 

 valleys between the Coast Range on the west and the 

 Sierra Nevada and the Cascade Ranges on the east, 

 where the amount in some cases does not exceed 10 

 inches, but in years of plentiful rainfall as much as 20 

 inches may fall in the best-watered parts. At Terrace 

 (Utah), a station on the Central Pacific Railroad, the 

 mean annual fall is only 4*3 inches, and in the driest year 

 was as low as 07 inch. To the eastward of the Rocky 

 Mountains the annual fall is from 10 to 18 inches, and 

 increases slowly to 60 inches on the Florida and Gulf 

 coasts, and from 40 to 50 inches in the Eastern States. 

 There is, however, a gradual decline both from the 

 Atlantic coast westward and from the Gulf coast north- 

 ward. In considering the various rainfall values in this 

 discussion allowance must he made for the position of 

 the gauges which are generally exposed on roofs, owing 

 to the stations being mostly in towns. It is well known 

 that the amount caught in the gauge decreases with alti- 

 tude above the ground, and it is estimated that the loss 

 from this cause in the values quoted by the Weather 

 Bureau is from 5 to 10 per cent, of the total annual 

 fall. With regard to the important subject of excessive 

 rainfall, down to the year 1888 only one self-recording 

 gauge was in use at the Signal Service stations ; five 

 others were added in 1889, and the publication in the 

 Monthly Weather Review of the maximum falls in five 

 and ten minutes, and also in one hour, were begun. Jn 

 August 1890 a cloud-burst passed over Palmetto (Nevada), 

 when a gauge that was not exposed to the full intensity 

 of the storm caught 8 8 inches of water in an hour, and 

 in August 1891, 11^ inches were measured within an hour 

 at Campo (California). The great majority of excessive 

 rains are said to occur east of longitude 105° W., and 

 principally in the summer months, in connection with 

 afternoon thunderstorms ; they occasionally take place 

 in the track of West India hurricanes, and are more 

 abundant on the Gulf and South Atlantic coasts than at 

 inland places. The maximum rates of rainfall per hour, 

 estimated from periods of five minutes, at the Weather 

 Bureau Stations which possess self-registering gauges, 

 were 9 inches at Bismarck (N. Dakota) ; 8'4 inches at 

 St. Paul (Wisconsin), and 8"2 inches at New Orleans. 



This valuable memoir has been prepared by Mr. A. J. 

 Henry, under the direction of Prof. Willis L. Moore, the 

 Chief of the Weather Bureau. 



NOTES. 



The German Emperor, as King of Prussia, has conferred 

 upon Dr. John Murray, Director of the Scottish Marine Station, 

 and formerly of the Challenger expedition, the rare distinction 

 of knighthood in the Order Pour le M^rite founded by Frederick 

 the Great. This is generally allowed to be the highest honour 

 which a man of science can receive, and is limited to thirty 

 German and twenty-five foreign knights. Lord Kelvin, Lord 

 Lister, and Sir G. G. Stokes are the only other British men of 

 science now alive who have received the Order. Dr. Murray 

 has also been elected a Foreign Member of the Imperial 

 Russian Academy of Sciences. 



The Committee appointed by the American Society of 

 Naturalists to inquire into the practicability and feasibility of 

 the exploration of the Antarctic continent, report that an 

 expenditure of from forty thousand to fifty thousand dollars 

 would suffice for an independent scientific expedition. The 

 Committee suggests that if this fund could not be raised by 



