io: 



NA TURE 



[May 31, 1883 



many were those of long-legged wading birds. But the most 

 interesting are those of the Mammoth and the problematical 

 so-called human tracks. About the Mammoth tracks there can 

 be no doubt. Some of these were uncovered by blasting in my 

 presence; lound basin-shaped impressions, 5 inches deep and 

 22 inches across, and occurring in regular alternating series, the 

 hind-foot tracking almost perfectly with the fore-foot. The 

 nature of the so-cilled human tracks, however, is far more 

 doubtful. These occur in several regular alternating series of 

 15-20. In size they are 18-20 inches long, and 8 inches wide. 

 In shape they are many of them far more curved than the human 

 track, especially in soft mud. The stride is 2\ to 3 feet, and 

 even more. The outward turn of the track is in many cases 

 greater than in human tracks, especially in soft mud. But the 

 most remarkable thing about them on the human theory is the 

 straddle, i.e. the distance between the right and left series. This 

 I found to be 18 and even 19 inches, which was fully as great as 

 that of the mammoth tracks. This is probably the greatest 

 objection to the human theory. On the other hand, the great 

 objection to the quadrupedal theory is the apparent singleness of 

 the tracks, and the absence of claw-marks. But it must be 

 remembered that the tracks are deep, and the outlines somewhat 

 obscure, and also that the mammoth tracks, on account of 

 tracking of hind with fore-foot, are in most cases, though not 

 always, single; 



After careful examination for several days, the conclusion I 

 came t > was that the tracks were probably made by a large 

 plantigrade qurdruped, most likely a gigantic ground-sloth, 

 such as the Mylodon, which is found in the Quaternary, or the 

 Morothenium, which is found in the upper Pliocene of Nevada. 

 The apparent singleness, the singular shape, and the large out- 

 ward turn of the tracks I attribute to the imperfect tracking of 

 hind and fore-foot on the same side, while the absence of claw- 

 marks was the result of the clogging of the feet with mud. 



This view seems to me most probable, 1 but many who have 

 seen the tracks think them human, and I freely admit that there 

 is abundant room for honest difference of opinion. On any 

 theory the tracks are well » orthy of scientific attention. 



Berkeley, California, May 12 Joseph Le Conte 



speedily determine whether the explanation here suggested is the 

 correct one. By way of illustration, I may mention that the water 

 of the ornamental pond in the centre of the Horticultural Gardens, 

 supplied clear and bright shortly before the opening of the Fisheries 

 Exhibition, had assumed within a few days and still retains the 

 colour and consistency of green-pea soup through the rapid de- 

 velopment, under the action of light, of a unicellular cryptogam 

 in the manner above described. W. Saville Kent 



Cloudiness of Aquarium 



Can you tell me the reason why the water in my fresh water 

 aquarium will not remain clear, but becomes cloudy throughout 

 in a few days after filling. 



The aquarium in question holds about twelve gallons of water. 

 It stands in a window facing north. I have in the water two or 

 three water- plants, among them a water-aloe. At the bottom 

 are small gravel stones, which have been thoroughly washed 

 before using. Floating on the surface for the benefit of a few 

 newts is a piece of virgin cork, on which is placed some carpet 

 moss. I had a dozen minnows and four newts to begin with, 

 but nine of the minnows and two of the newts have died, mani- 

 festly from the fouling of the water. 



The framework of the aquarium is iron, with a slate floor. 

 The glass sides are fixed with red lead. There is a copper tube 

 for overflow purposes, which was inserted when a fountain was 

 used in the centre. This has now been removed and the water 

 is stagnant. 



It is now some years since I have kept an aquarium, and I 

 cannot divine the reason for the above-mentioned cloudiness of 

 the water. I shall be much obliged if you or some of your cor- 

 respondents will help me. X. 

 May 9 



So far as I can judge from " X's" description, the cloudiness 

 of the water in his aquarium is due to the abnormal develop- 

 ment of some unicellular ali;al (Palmellacea;) or to the prolific 

 spore-production within it of one of the filamentous forms (Con- 

 fervacea:). This may be obviated by screening the back of the 

 tank from the access of light. Possibly "X" may find on 

 examination that the cistern whence he obtains his supply has 

 been left uncovered, and that the intruding algal has established 

 itself and entered upon the reproductive process in that position. 

 In that case he should either i-olate the water he requires in a 

 dark place for a week or so, when the spores will die, or obtain 

 his supply from a purer source. An investigation with a high 

 po ver of the microscope of the turbid water complained of will 



1 Views similar to my own have recently been expressed by Prof. Marsh 

 and by G. K. Gilbert. 



Singing, Speaking, and Stammering 



Referring to the letters in Nature (vol. xxvii. p. 580) on 

 my classification of vowel sounds, allow me to explain : — 



The classification given in the " Principles of Elocution" (4th 

 ed., 187S) was retained from the earlier editions of that work, 

 because of the difficulty, or impossibility, of exhibiting the com- 

 plete vowel system of visible speech without V. S. symbols. For 

 the purposes of the book on Elocution, the latter were not 

 required ; but a note (on p. 36) immediately preced ing the 

 " General Vowel Scheme " explains the basis of the complete 

 classification developed in visible speech. 



As you have given an abstract of my classification, quoted by 

 Dr. Stone from " Principles of Elocution," I shall be glad if you 

 will show your readers the following abstract of the visible 

 speech classification : — 



Classification of Vowels in Visible Speech 



Nine Lingual positions yield 



9 Primary vowels 



Each Primary vowel yields 



a "Wide" variety by 



faucal expansion = 9 Wide 



vowels 



Each Lingual vowel yields 



a "Round" variety by > 



labial contraction ) 



Each Normal vowel yields a possible variety by higher, lower, 



broader, or narrower formation = 36 + 144 = a total of 180 



vowels. 



The mutual relations of the different sounds may be exhibited 

 in this way : — 



Lingual, 



18 Lingual 

 vowels. 



;l8Labio-lingual 

 vowels. 



= 36 Normal 

 vowels. 



Primary. 



Wide. 



Labio-li 



In this arrangement, each No. I, No. 2, N ■. 3, &c, in the 

 four sets is formed from one and the same lingual position. 

 These relations are plainly exhibited in the symbols of visible 

 speech. Thty cannot be shown by ordinary letters, but the use 

 of numbers, as above, may make the arrangement clear to those 

 who are not acquainted w ith vi-ible speech. 



Washington, D.C., May 12 Alex. Melville Bell 



On the Cold in March, and Absence of Sunspots 



I was travelling when Dr. Woeikof's letter appeared in 

 Nature (vol. xxviii. p. 53), and could not sooner reply to his 

 criticisms on my communication (vol. xxvii. p. 55>)> " Unprece- 

 dented Cold in the Riviera— Absence of Sunspots." Let me 

 first remark that I do not go so far as to "ascribe (as Dr. 

 Woeikof says that I do) the great cold of March, 1883, at the 



