December 30, 1898.] 



SCIENCE. 



947 



confined to such cases as those mentioned. 

 The production of liquid ammonia in quan- 

 tity has led to its investigation as a solvent, 

 in which it resembles water to some consid- 

 erable degree. Salts render it a conductor 

 of electricity and a similar dissociation 

 seems to take place as in aqueous solution. 

 In the December number of the American 

 Chemical Journal E. C. Franklin and C. A. 

 Kraus record the solubilities of something 

 over five hundred substances, inorganic and 

 organic, in liquid ammonia in which many 

 analogies with water are shown. They also 

 give the determinations of molecular rise 

 in boiling-point of liquid ammonia for 

 twenty- nine different substances. 



J. L. H. 



CURRENT NOTES ON METEOROLOGY. 

 UPSALA CLOUD OBSERVATIONS. 



The first publication embodying the re- 

 sults of the International Cloud Observa- 

 tions comes from Upsala, where Dr. Hilde- 

 brandsson carried on the work during the 

 International Cloud Year (May 1, 1896- 

 May 1, 1897). According to Nature (Dec. 

 1) nearly 3,000 measurements of heights 

 and velocities were made, 1,635 of which 

 were made by means of photography. The 

 annual variation of the mean heights of the 

 clouds is very marked, the maximum com- 

 ing in June and July, and the minimum in 

 the winter. During the summer the mean 

 height of the cirrus is 8,176 meters, and of 

 the cumulus 1,685 meters. The heights of 

 the upper and middle level clouds are lower 

 than at Blue Hill Observatory. The veloc- 

 ity of all the clouds is greater in winter 

 than in summer. 



RECENT ANEMOMETER STUDIES. 



At the meeting of the Eoyal Meteorolog- 

 ical Society, held in London, November 16th, 

 a report on the exposure of anemometers 

 at different elevations was presented by the 

 Wind Force Committee. The experiments 



were carried out by Dines and Wilson- 

 Barker, on board H. M. S. Worcester, off 

 Greenhithe. Five pressure-tube anemom- 

 eters were employed, the first being at the 

 mizzen royal masthead ; the second and 

 third at the ends of the mizzen topsail yard- 

 arm, and the fourth and fifth on iron stand- 

 ards 15 feet above the bulwarks. The re- 

 sults show that the ship itself affected the 

 indications of the lower anemometers, while 

 some low hills and trees, which were a 

 quarter of a mile away from the ship, to 

 the south and southwest, also affected the 

 wind velocity from those quarters. The 

 Committee are of the opinion that the 

 general facts deducible from these observa- 

 tions bearing on the situation of instruments 

 for testing wind force are : ' (1) That they 

 must have a fairly clear exposure to be of 

 much value, and it would appear that for 

 a mile, at least, all around them there 

 should be no hills or anything higher than 

 the position of the instruments. (2) That 

 on a ship the results may be considered 

 fairly accurately determined by having the 

 instrument 50 feet above the hull, but that 

 on land it will generally be necessary to 

 carry the instrument somewhat higher, to 

 be determined entirely by local conditions. 

 (3) That no other form of anemometer offers 

 such advantages as the pressure-tube, from 

 the fact that it can be run up and secured 

 easily at this height above a building, and 

 that the pipes and stays can be so slight as 

 to offer no resistance to the wind or cause 

 any deflecting currents. 



SAN FRANCISCO RAINFALL. 



A PAPER by Marsden Manson in the Oc- 

 tober number of Climate and Crops, California 

 Section, concerns the seasonal and monthly 

 rainfall at San Francisco from 1849 to 1898. 

 In this period of forty-nine years the nor- 

 mal annual rainfall has been 23.4 inches. 

 Fluctuations have occurred between an an- 

 nual rainfall of 7.4 inches in 1850-51, and 



