March 25, 1887.1 



sciEJsrcE. 



291 



■embarrassment. The excellent character of the 

 scientific work done in many of them is justly 

 adduced as a reason for the request. 



Prof. A. W. Williamson, F.R.S., has just re- 

 signed the chair of chemistry at University col- 

 lege, London. W. 



London, March 7. 



GEOGRAPHICAL NOTES. 



Africa. 



J. T. Last, commander of the London geo- 

 graphical society expedition to the Namuli Hills 

 in East Africa, has sent a report of his trip to the 

 south end of Lake Nyassa. Some of his remarks 

 are of general interest. Starting from the mission 

 station at Blantyre, he passed by Lake Shirwa, 

 «,scended Mount Zomba, which he found to be five 

 thousand feel high, and visited the country of the 

 Angoni, south-west of Lake Nyassa. He states 

 that the district around Zomba proves to be very 

 fertile. The English plantations in that district 

 have fine crops of coffee. The culture of tea, 

 cocoa, and arrowroot is being tried, and they prom- 

 ise to do well. On his way north he crossed the 

 Shire, the eastern bank of which is quite unin- 

 habited, while the western one is well-peopled and 

 very fertile. As the kings of the Angoni and 

 "Yao — which latter live on the Shire — have made 

 some terms of friendship, the petty wars between 

 the tribes have ceased, and Last travelled without 

 any trouble arising from this source. At the out- 

 let of the Nyassa he encountered a low and sandy 

 cotmtry with numerous patches that are covered 

 with water during the wet season, salt being de- 

 posited when the water evaporates. The Angoni 

 -district, south-west of the Nyassa, forms a large 

 plateau about five thousand feet high, which ex- 

 tends far west. In all this district there is scarcely 

 a tree to be seen, and the fuel commonly used by 

 the people is cornstalks and ox-dung. The land 

 near the east is very poor, but as one proceeds to- 

 wards the west it greatly improves in appearance, 

 and in its western portions it is extensively culti- 

 vated. The expedition returned to Blantyre on 

 the 1st of July. On the 12th they left again, and 

 -arrived at the Namuli Hills in August. 



The Spanish traveller Sorela Fajardo arrived on 

 the Senegal on Feb. 27. He proposes to cross the 

 continent from west to east, starting from St. 

 Louis in Senegambia. 



America. 



N. S. Shaler discusses in his paper on * Fluvia- 

 tile swamps of New England' {Amer. journ. sc, 

 March, 1887) the formation of river-valleys in New 

 England, more particularly in eastern Massachu- 



setts. A comparison between the rivers flowing 

 north and those running south shows a great dif- 

 ference in the character of their valleys. The 

 former have excavated the glacial deposits which 

 filled their valleys, and deposited alluvial plains 

 that have distinct terraces The erosion of the old 

 deposits is still continuing. The rivers running 

 south have excavated part of their glacial de- 

 posits, but the process ceased a long time since. 

 None of them have sufficiently strong current to 

 clear their beds from the detritus carried into them 

 by floods from their tributaries, and coarse sedi- 

 ments are continually being deposited in their val- 

 leys. Shaler supposes that these plains were formed 

 while the river was at a lower level than it is at 

 present, and became swampy by the same changes 

 on the drainage conditions which have so ob- 

 structed the flow of the stream. These facts 

 tend to show that the northern slope of the valleys 

 has been diminished. Thus the eroding force of 

 the rivers which run south has increased, while 

 that of those running north has so much decreased 

 as to stop their eroding action. Shaler estimates 

 the tilting of the land necessary to have this 

 effect to be two feet to the mile, and concludes, 

 from the well-known observations on submerged 

 forests on the New England coast, that it consisted 

 in a lowering of the southern part. The result of 

 his researches as to the recent geological history of 

 this district are that the uneven glacial banks were 

 deposited while the land was submerged. When 

 the ice retreated, a re-elevation took place, after 

 which the glacial deposits were rapidly excavated. 

 With the disappearance of the ice from the con- 

 tinent, the southern portion became lower again, 

 and the latter movement produced the swampy 

 character of the valleys of rivers running north 

 by putting an end to the eroding action of their 

 waters. 



The Mississippi River commission has just issued 

 a map of the alluvial valley of the Mississippi River 

 from the head of St. Francis Basin (latitude 37° 20' 

 north) to the Gulf of Mexico, showing lands sub- 

 ject to overflow, the location of levees, and trans- 

 alluvial profiles, on a scale of five miles to an inch 

 (1:316,800). The topography is reduced from de- 

 tail maps and surveys made by the various gov- 

 ernment offices and railroads. The object of the 

 map being to illustrate the floods of the Missis- 

 sippi, the district which is subject to overflow is 

 marked by brown hachure lines, the hydrography 

 and lettering being printed in black. A great 

 number of section-lines and the profiles belonging 

 to them are embodied in the map. The profiles 

 show the high-water line of 1883. Though these 

 profiles are of a darker brown than that of the dis- 

 trict subject to inundation, they somewhat dis- 



