March 12, [896] 



NATURE 



439 



pointed out. The author then turns to the slow disin- 

 tegration of glaciated surfaces contrasted with the easily 

 rotted and fertile volcanic soils, and describes the suc- 

 cession of vegetable organisms in reclaiming new soils, 

 and gradually rendering them suitable for tillage, begin- 

 ning with the most humble, and passing up to the more 

 conspicuous plants, and those useful for the purposes of 

 man. 



We next proceed to the ordinary types of soil in the 

 valleys and plains, and opportunity is taken to give the 

 life-history of soil from its first separation from the parent 

 rock, all through its slow journey down the hillside, until 

 it passes out to the streams and the sea. The action 

 of frost and rain, of snow and wind, of carbonic acid and 

 oxygen, but not of the very important humus acids, is 

 given in full detail, and the great importance of wide- 

 spread forest vegetation in preparing the soil for sub- 

 sequent tillage by deep disintegration is rightly insisted 

 on. The pumping of air in and out of the soil by rain 

 and evaporation is shown to be of vast use, not only to 

 the larger plants, but to the bacteria and fungi, which 

 are of such great import in the life and death of higher 

 organisms. 



A capital series of pictures illustrates this monograph ; 

 one can only wish that in all cases the localities were 

 specified. The function of roots, whether alive or dead, 

 is well described. Darwin's work on earth-worms is 

 referred to, and the operation of beetles, ants, crawfish, 

 burrowing birds, reptiles, and rodents dealt with. 4 

 section of the paper relates to deposited soils, and 

 great stress is laid on the circulation of soil and the 

 functions of materials, which are the sur\'ivals of rocks 

 which may have long ago disappeared, but whose in- 

 fluence in the soil does not pass away for very long 

 periods. Certain peculiar soils, such as those of swamps, 

 marine marshes, and sand dunes, are not neglected, and 

 prairie soils are explained as due to the destruction of 

 forests by fire. Man and the soil succeeds, and it is 

 pointed out how great an action and reaction there is 

 between these two, so that not only the distribution of 

 disease, but even that of slavery can be shown to have 

 a distinct direction with the soil. The following words 

 may be noted in conclusion : " A heedless neglect of our 

 duty toward it has led to the destruction of the soil over 

 an aggregate area of not less than 4000 square miles. 

 This means the loss of food-giving resources which would 

 be stifficient, with proper care, to support a population 

 of about one million people." 



Prof. Shaler contributes to another annual report ^ a 

 valuable and original article on the geological conditions 

 of harbours. The following. types are of importance in 

 the United States, and it would be easy to recognise 

 them elsewhere : — 



Delta harbours ; the Mississippi. 



Re-entrant Delta harbours ; Mobile Bay. 



Glacial or Fiord harbours ; Cape Breton. 



>[ountain Range harbours ; Lower California and North 



of Puget Sound. 

 Moraine harbours ; East end of Long Island, 

 Lagoon and Sandbar harbours ; Chatham harbour. 

 Sand-spit and Travelling Beach harbours ; Provincetown 



harbour on Cape Cod. 

 Coral Reef harbours ; Florida and Atolls. 

 Volcanic Crater harbours ; not known in the States. 



Prof. Shaler points out how important good harbours 



ire in developing a race of sailors, and through them 



quiring commerce and influence. His te.xt is pointed 



y refereoce to the fact that the English-speaking race, 



their kindred, the Dutch, possess nine-tenths of the 



ikiable islands beyond the limits of Europe, and that 



\orth Europeans bid fair in time to dominate every part 



of the world fit for their occupation. " These considera- 



^ Thirteenth Annual Report of the United States' Geological Survey, 

 1891-92. (1893.) 



NO. 1376, VOL. 53] 



tions make it plain that the way to national power is 

 over the waves, and that this way is the natural path of 

 our race." 



It is essential that a good harbour should fulfil the 

 following conditions : — 



It should be protected from the incursion of heavy 

 waves. 



There should be a deep and roomy channel from the 

 anchorage to open water. 



There must be ample room to receive and discharge 

 cargoes. 



It should be convenient for access from the interior. 



In addition to this, it should be roomy, not in the 

 path of heavy currents, not liable to shifting channels or 

 deposits, nor likely to be obstructed at any time by 

 ice. Harbours may be injured in greater or less degree 

 by floods, winds, tides, by movements of the solid land, 

 and by the indirect consequences of all these causes. 

 The great preserxers are the scour of tides and currents ; 

 the great destroyers, sediment and the growth of organisms. 

 The action of sediment is fairly well understood and 

 allowed for by engineers, but the influence of animals and 

 plants is here dealt with in more detail than we remember 

 to have seen elsewhere. The protecting work of alga; 

 and seaweed is thoroughly explained, and the " eel-grass " 

 {Zosfera viaritima) described in detail ; this seems to 

 have great influence in arresting the deposit of sediment, 

 and causing the silting-up of harbours. The general 

 operation of the tide-water grasses is to diminish the 

 area of the harbour, and to deepen the channels which 

 remain ; that of mangroves is to occlude the harbour by 

 cutting out the storage of water at high tide. The de- 

 structive work of plants appears to far exceed that of 

 polyps. The article concludes with a review of the 

 whole coast-line of the States, and the origin of all the 

 important harbours. 



The article on potable waters, by Mr. McGee,* con- 

 tains a good deal of useful information, from the building 

 of cisterns to the fouling of well-water by cesspools. 

 Direct rain-water supplies are first dealt with, and the 

 necessary filtering, which such water needs, described ; 

 next stream-water, and then that from shallow and deep 

 wells, the latter source being termed phreatic water, 

 whether from deep-seated springs, from artesian wells, 

 or deep-pump wells. 



Dr. A. C. Peale, who has done such an immense amount 

 of unassuming and scarcely appreciated work for the 

 survey in past years, contributes a much more important 

 paper on natural mineral waters of the country.-' This 

 includes a table of all mineral springs which yield more 

 than 1000 gallons per hour ; these number more than 120. 

 Mineral springs are found to be usually associated with 

 areas of sedimentary rock, particularly in the neighbour- 

 hood of mountain ranges, where they have suffered much 

 disturbance, and where volcanic action is now, or recently 

 has been, rife. The annexed classification is adopted : — 



(A) Non-thermal. 



(B) Thermal. 



(i) Alkaline. 



(2) Alkaline-saline. 



(3) Saline. 



(4) Acid. 



Each of the four last divisions is again divided into 

 sulphated and muriated, and the last into siliceous as 

 well. It is recommended that, in future, analyses shall 

 conform to the scheme laid down by the Chemical Society 

 of Washington, the most important points in which seem 

 to be that solids shall be expressed in parts per million, 

 and that the radicles actually found shall be expressed ; 

 while the chemist is at liberty to express, in addition, the 

 probable state of combination in which the different in- 

 gredients occur. A brief account is given of the various 



1 Fourteenth Annual Report of the United .Suites' Geologic.il Survey, 

 1892-93. (1894.) 2 Ibid. 



