Makch 15, 1907] 



SCIENCE 



435 



THE BRUCKNER PERIOD OF RAINFALL AT RIO 

 DE JANEIRO 



A RECENT study of rainfall at Eio de 

 Janeiro, summarized in the Meteorologische 

 Zeitschrift for January, 1907, shows that a 

 thirty-five-year periodicity seems to prevail 

 there. It is interesting to observe the increas- 

 ing number of cases of periodicity in climatic 

 averages which fall in line with the Briickner 

 period. An important difference between the 

 original work by Briickner and these later in- 

 vestigations is, however, this : that Briickner 

 started on his quest without prejudice in favor 

 of any particular period, while the more recent 

 students of the same subject have naturally 

 been prejudiced by the conclusions reached by 

 the author of the now famous ' Klimaschwan- 

 kungen seit 1700.' 



METEOROLOGICAL PHENOMENA OF VOLCANIC 

 ERUPTIONS 



The inflowing air currents towards vol- 

 canoes which are in active eruption, and the 

 local whirlwinds which are sometimes gen- 

 erated in these currents, have been described 

 by several writers. During the last eruption 

 of Vesuvius (April, 1906), as pointed out by 

 W. H. Hobbs (Journ. Geol., 1906, 636-655) 

 the windows of some houses were broken on 

 the side away from the mountain. This is 

 explained as having been due to the strength 

 of the air currents which were moving towards 

 the volcano. 



TREE-PLANTING FOR SNOW-BREAKS 



Tree-planting has been begun along the 

 western lines of the Canadian Pacific Railway. 

 Over one hundred miles of trees are to be 

 planted between Calgary and Winnipeg for 

 snow-breaks. Experiments are to be made 

 with tamarack for use as ties, and plantings of 

 jack pine and tamarack are to be started at 

 Medicine Hat in this connection. 



The general title under which these ' Notes ' 

 have been printed since 1896 is changed with 

 the present number of Science from Gurrent 

 Notes on Meteorology to Current Notes on 



Meteorology and Climatology. The latter 

 title expresses more clearly the scope of the 

 subjects which are here included, and gives 

 deserved prominence to the geographical 

 aspects of meteorology which are properly em- 

 braced in the term climatology. 



E. DeC. Ward 

 Haevabd Univebsitt 



PHOTOGRAPHS OF FAINT STABS'- 

 The number of facts now being accumu- 

 lated by means of photographs of the stars is 

 enormous. Unfortunately, only a small por- 

 tion of these facts is now available, and there- 

 fore of any use to science. This applies par- 

 ticularly to the faint stars. Many photo- 

 graphs are taken by professional and amateur 

 astronomers, which are followed carefully 

 during long exposures with telescopes having 

 large apertures. In some cases, several hun- 

 dred thousand stars appear upon a single plate. 

 Unfortunately, no record has been published 

 of many of these photographs, and therefore 

 no use can be made of them. It is the object 

 of the plan described below to remedy this 

 diflB.culty. 



The Harvard collection of photographs in 

 part supplies this need, for stars of the thir- 

 teenth magnitude and brighter. On the av- 

 erage, this collection contains images of all 

 the stars of the fifth magnitude and brighter 

 on over a thousand nights. The number of 

 these stars is about two thousand, the photo- 

 graphs are distributed throughout the last 

 twenty years, and cover all parts of the sky. 

 For stars of the twelfth magnitude, which can 

 be taken with a lens of one-inch aperture and 

 an exposure of one hour, the number is re- 

 duced to five hundred. This includes the 

 stars in the Harvard Map of the sky, about 

 two million in number. There are about five 

 million stars of the thirteenth magnitude and 

 brighter. They appear on plates taken with 

 eight-inch doublets, and having exposures of 

 ten minutes. About two hundred images of 

 each of these are contained in the Harvard 

 collection. For fainter stars, the number of 

 images falls off very rapidly. Stars of the 

 ' Harvard College Observatory, Circular 123. 



