February i, 1894] 



NA TURE 



3^5 



lectly satisfactory results." He continues: "But it is to be 

 regretted that the United States Postal Department should, in 

 another way, continue to maintain a barrier against cheap trans- 

 mission and interchange of specimens. The sample post can, in 

 any case, only be used for small packets, but larger packages 

 can now be sent to nearly all foreign countries by parcel post, 

 the introduction of which was an inestimable boon. The 

 United States Government stands almost alone in persistently 

 refusing to cooperate in this respect." 



As chairman of the committee appointed by this Academy to 

 prepare the circular, I have obtained from Mr. N. M. Brooks, 

 Superintendent of Foreign Mails, U.S. P.O., certain official 

 information which, it is believed, will throw a new light on Mr. 

 McLachlan's comments, and make the desirability of sending 

 specimens by sample post still more evident. 



Mr. McLachlan's quotation from the letter of the British 

 Postal Secretary mentions the fact that specimens of natural 

 history do not come within the Postal Union's definition of 

 sample packets. Mr. Brooks, in a letter of July 14, 1893, 

 writes : " Said proposition [to admit such specimens as 

 'samples'] having been formally submitted to a vote of the 

 countries of the Postal Union, and having failed to receive the 

 support of the number of countries necessary to secure its 

 adoption, no country of the Postal Union is at liberty to trans- 

 mit by mail to another country of the Union, natural history 

 specimens as ' samples of merchandise.' " 



On the subject of the parcels post, Mr. Brooks states (letter 

 of January 12, 1894): "It may be well to say that so far as 

 sfnall packages of natural history specimens are concerned, the 

 parcels post woald afford but few additional facilities over those 

 offered in the regular mails if the rates were assimilated to those 

 in force in Great Britain and Canada ; for instance, the lowest 

 charge in Great Britain on a package weighing 3 pounds or less 

 addressed for delivery in Belgium is i shilling 3 pence ( = 30 

 cents), and to France i shilling 4 pence (=32 cents), while in 

 Canada the charges for a pound or less would be to Belgium 

 46 cents, and to France 48 cents. While the sums above 

 named may be low for the transmission of three-pound or one- 

 pound packages, it must be remembered that these sums are 

 the minimum charges, and must be paid also on smaller 

 packages, even on packages weighing only one or two ounces. 

 If the proposition of this department to admit natural history 

 specimens to the mails as ' samples ' had been adopted, small 

 packages of such specimens would have been transmissible 

 throughout the extent of the Postal Union at the rate of one 

 cent for each two ounces, while the facilities offered by the 

 parcels post for the transmission of larger packages would not 

 have been curtailed. For example, under present conditions a 

 package weighing 4^ ounces may be sent from Canada to 

 Belgium or France as a kiter upon the prepayment of 45 cents ; 

 as a parcels-post package the charge would be 46 and 48 

 cents respectively; as a 'sample' the charge would be 3 

 cents." 



Such a large proportion of the packages contain speci- 

 mens weighing less than a pound, that the establishment of a 

 "samples" rate of postage for them is in the highest degree 

 desirable. 



In the present condition of affairs it would appear that the 

 "hyper-protection," at which Mr. McLachlan hints in his con- 

 cluding sentence, is not on tJiis side of the Atlantic. 



Philadelphia, January 18. Philip P. Calvert. 



The Origin of Lake Basins. 



The present, while the origin of lake basins is under discus- 

 sion in your pages, seems a favourable opportunity for collect- 

 ing all that can be said for and against the glacier theory. Not 

 being a geologist myself, I do not know whether the few remarks 

 I have to make may be new or not. They are therefore sub- 

 mitted with great diffidence for the consideration of experts. 



If lake basins have been excavated by boulder-shod glaciers, 

 then it follows, that as these boulders do not act by cutting, 

 but by grinding, the boulders will be worn away as much as 

 the rock beneath them ; that is, forevery square yard excavated, 

 there will be an equal amount of boulder material ground down. 

 This will be so, as we are hardly entitled to assume that the 

 boulders are on the average harder than the under rock, and as 

 they are in smaller pieces, they will be liable to a greater 

 amount of fracture. Are theglacialists, then, prepared to supply 

 an amount of boulder material equal to the amount excavated ? 



NO. 1266, VOL. 49] 



and if not, how do they explain the greater cutting power of 

 the moving blocks ? Further, after the glacier has dug a 

 basin, the flow of water under the ice will be very slow, owing 

 to the widening of the glacier, and the water spreading across the 

 whole breadth of the basin. How, under these conditions, is the 

 abraded material got quit of? It will no longer be water-borne, 

 but will probably be pushed upwards and forwards out of the 

 basin by the ice and boulders, and should therefore form a 

 deposit of a breadth nearly equal to that of the basin. Is there 

 any evidence of this ? 



Another point to which I wish to refer is in explanation of 

 the constant association of lakes with evidences of previous 

 glacial conditions. It is possible, as has been pointed out by 

 Mr. Oldham, that this relation may only be apparent, and that 

 there may be rock basins that are not lakes, and that the only 

 part the ice played was to keep these basins from being filled up 

 by deposits. There, however, seems to be another way in which 

 the ice may have acted and at least helped to make the lake 

 basins. When we examine the position of the principal lakes 

 in Switzerland and Italy, we find that many of them lie where 

 the plains merge into the mountains, that is, close to the foot 

 of the mountains. In many of them the lower part of the lake 

 extends into the plains, while the upper part penetrates the 

 mountain range. Now, the foot of the principal slope is where 

 the greatest accumulation of ice will occur. The quick upper 

 slopes supplying more ice than the lower slopes can take away, 

 the consequence is that the ice accumulates until its greater depth 

 compensates for its slower movement. If, then, the surface of 

 the land was in equilibrium in the shape it was in before the ice 

 made its appearance, then, owing to the unequal distribution of 

 the load, it would evidently not be in equilibrium after the 

 arrival of the ice, and the consequence would be that wherever 

 the ice was deepest there would be the greatest tendency for a 

 depression to form on the surface of the earth. In this way 

 basins would tend to form under the places where the ice was 

 deepest ; this would naturally be in, and in front of, the main 

 valleys in the line of the greatest liow of ice, at the point 

 where the quick slope of the valley gives place to the 

 slow slope of the plain, just where we find the principal 

 Alpine lakes. The formation of lake basins in this way will of 

 course be greatly modified by the nature of the under rock. We 

 could easily imagine basins such as those of the Lake of Zurich and 

 the Lake of Varese to be formed in this way, as the shores slope 

 easily in all directions ; but it is much more difficult to imagine 

 the upper ends of the greater Alpine lakes, where the shores 

 are precipitous, to be produced by sinking due to the load of 

 ice. It might be objected that if these lake basins were pro- 

 duced in the way suggested, the earth's crust ought to have re- 

 covered its form after the Ice Age had passed. This, however, 

 is by no means a necessary conclusion, because when sinking, the 

 rocks being already fractured, deformation can take place com- 

 paratively easily ; but when rising, the rocks, being in arch-form, 

 are in a much better position to resist an upward thrust than 

 they were to resist a downward one. The result of the snow and 

 ice melting would probably be to cause a general elevation of 

 the mountains as well as of the lakes. John Aitken. 



Darroch, Falkirk, January 20. 



I have been following with some interest the recent dis- 

 cussion in these columns concerning the power of ice to erode 

 rock basins, since I have prepared for publication (presented at 

 the December, 1893, meeting of the Geological Society of 

 America) a paper describing some recent studies of my own 

 upon this subject. After several years of study in the glacial 

 belt of New England, having never found definite evidence of 

 rock basins in lakes of large size, I came to the conclusion that 

 the theory of rock basins had little value, particularly since, 

 after having been before us for more than thirty years, so few 

 instances have been proven. In my own case, and I believe 

 also in others, the attempt had always been to trace a con- 

 tinuous rock line, and this I now believe to have been an 

 entirely wrong method ; for how many large lakes are there in 

 which possible outlets may not be buried beneath drift areas? 



By following an entirely different method I have been able 

 to prove that Lake Cayuga in central New York, and probably 

 also Lake Ontario, is in a rock basin. Lake Cayuga has a 

 length of nearly forty miles, and a width varying from one to 

 nearly four miles, while its depth is in one place four hundred 

 and thirty-five feet, the bottom being considerably below sea- 

 level. 



