3 20 



NA TURE 



[August 3, 1882 



of mountains is calculated, and to which barometrical readings 

 are reduced. 



'I bis as-umption, however, is called in question by several 

 mathematicians, who allege that the sea-level is by no means 

 that of a regular spheroid, as is generally supposed, but may 

 vary many hundreds of feet i:i level even along the same parallel 

 of latitude, quite independently of the temporary action of winds 

 cean current-. 



According to the law of gravitation, all sub,tances attract one 

 .-11 ther with a force proportional to their masses. A continent of 

 lind will therefore exert an attractive influence upon the sea, 

 it to rise upon its shores to a height which will vary 

 according to the mass of land that causes the attraction, and 

 mnt, it is said, to as much as 1000 metres above the 

 level to which the sea attains in mid-ocean. This extraordinary 

 result is deduced by Ph. Fischer from a discussion of pendulum- 

 ins, and somewhat similar conclusions are arrived at by 

 and Heinrich Brims. 



Founding upon these observations, a German geologist, Dr. 

 I'enck, has proposed an explanation of the phenomena presented 

 by the raised beaches, and other tokens of oscillation in the sea- 

 level, which are so conspicuous during the glacial period. If 

 the land has the property of thus drawing the sea towards it in 

 proportion to its ma-s, it follows that anything which adds to 

 that mass will increa-e the effect, and thus a great thickness of 

 glacier-ice laid upon a continent, will draw the water towards it, 

 and raise the sea-level in its immediate vicinity ; and, according 

 as the ice increases or diminishes, so will the level of the sea 

 rise or fall in proportion. Moreover, the altitude of the sea- 

 beach may vary considerably, it is said, along the border of one 

 and the same continent, by reason of the varying thickness of the 

 ice in different parts. In this way it is conceived an explanation 

 is found for the fact that in Norway the old terraces and sea- 

 beaches do not coincide in level, but vary in altitude at places not 

 very far distant from one another. The action of the ice may 

 in short be so localised that its attractive force will vary consi- 

 derably along the same line of coast. 



The-e views are certainly somewhat different from those that 

 have hitherto prevailed in regard to the regularity of the sea-level. 

 If there is such a very great difference in the height to which 

 the surface of the sea may attain in different places, the baro- 

 meter should give more indication of it than it seems to do. 

 be desired that every means should he 

 taken to ascertain the relatix :- height of the sea in various places 

 so chosen as to test the truth of the views 1 have mentioned. 

 The apparent connection between glaciation and submergence is 

 now attracting notice in various quarter-. Dr. I'enck maintains 

 that shifts in the relative level of sea and land go hand in hand 

 with oscillations in the glaciation. In 1865 I called attention 

 to this connection, and suggested what seemed to me to be a 

 p 'Ssible explanation of it ( ee fount, of the Geol. Soc. vol. xxi. 

 p. 178). 



Penck's views, it will be seen, are somewhat different from 

 those of Adhemar and Croll, to which he points out sever 1 

 objections. His memoir i- entitled " Schwankungen des 

 Meeresspiegels," and appears in the Jahrlmch der Geograpli. 

 Gesillschaft c« Miinchen, C 



T. F. JAMIESOX 

 Ellon, Aberdeenshire, July 31 



Voice in Lizards 

 The above heading in Natui i. . 1. xxvi. p. 29, rather 

 surprises me, as though voice- in lizards were a recent discovery. 

 The loud and plaintive "gui— gui — gui " made by the large land 

 lizard of that name, has been well known to met' 

 seventeen years, and is of course well kn on to every Assamese. 

 The call is always heard in twilight, in the depths of the forest, 

 and when once heard isnotmistakableforthatofany other animal. 

 It is plain, monotonous, loud, and repeated with two second in- 

 tervals some eight or ten time-, when there is a pause of about 

 two minutes, and it is repeated. For those who do not under- 

 stand the Hunterian system of spelling I would write it gooee — 

 gooee, the 00 most prolonged. The gui is about 3 to 3A feet 

 long— from snout to tip of tail — which latter exceeds the body 

 and head. Colour grey-green, with clear yellow scales here and 

 there — at times grouped — and that gives a mottled appearance. 

 The tail has a double row of sharp scale-spines along its cre,-t, 

 and if suddenly lashed can cut the skin of any bare-legged 

 bystanders. 



It lives in holes under, or in, tree stems, often as high up as 

 30 or 40 feet. The flesh i- eaten and prized, the skin u-ed as the 

 membrane in s ime kind- of guitars. There seem several kinds, 

 one of 3 or 34 feet, another larger— both land lizards — a still 

 larger kind frequent- the rivers, up to 6 feet or more in length. 

 It hi-ses like the larger snakes, and the peculiar call that gives 

 it the name "gui," can be heard in still forest I should say a 

 mile ; one that repeats this monotonous call every evening is 

 loud en. mgh to be an annoyance at times, though it is over 500 

 yards off. s. E. Peal 



'on-, As-am 



Halo 



About 2 p.m. to-day a remarkable halo was visible here. 

 The sky was partially covered with light cirrus clouds, and some 

 small fleecy drift was rapidly moving from the north-west at a 

 low altitude. I saw a bright bow at about 45 from the sun 

 nearly due north, extending over a clear portion of the sky ; this 

 gradually extended till it formed a circle with the sun in the 

 most southern point of its circumference. The width of the 

 bow was rather grea'er than the diameter of the sun, the whole 

 circle being, as near as I could judge, 45 or 50° in diameter. 

 It was brilliantly white, brighter than the white of any clouds in 

 the neighbourhood ; it lasted perhaps fifteen minutes, and gradu- 

 ally broke up and fade I. I couki see no other interesting halo 

 nor any appearance of parhelia. YV. A. Sanford 



Tynehead, Somerset, July 25 



THE ELECTRIC PROPERTIES OF FLAMES 



THE electric properties of flames have often invited 

 the investigation of physicists, but the obscurity and 

 contradictory nature of some of the phenomena have been 

 such that in spite of a large number of researches no 

 complete account of these properties has hitherto been 

 given. Most of these researches are enumerated in a 

 paper contributed by Prof. Holtz to Carl's Repertorium 

 last year ; but though Holtz has himself added to our 

 knowledge of the electrical property of flames by his re- 

 searches on the behaviour of flames when employed as 

 electrodes, he left much yet to be investigated in this 

 department. 



The late-t contribution to our knowledge of the subject 

 appears in the current volume of Wiedemann's Annalcn 

 der Physik und Ckemie, from the joint pens of Herren 

 Dr. Julius Elster and Hans Geitel. As the results of 

 their investigations go far to clear up some of the points 

 which have hitherto been obscure or contradictory, some 

 account of these investigations will probably not be un- 

 acceptable to the readers of Nature. 



The chief theories that have been advanced from time 

 to time in explanation of the electrical properties of 

 flames may be reckoned as three in number. 



1. Pouillet in 1S27 propounded the suggestion that the 

 electricity of flame is due to the process of combustion as 

 such, and therefore presumably analogous to the electrifi- 

 cation observed by Volta to result when a burning coal or 

 pastille is placed upon the cap of an electroscope. 



2. Matteucci, in 1854, explained the phenomena by 

 supposing that the flame acted upon the two metal 

 electrodes (employed to test its electrification) as an 

 electrolyte'; in fact, that it acted as the acid between the 

 two metallic phtes of a voltaic cell ; a view which practi- 

 cally agrees with that earlier propounded by Hankel. 



3. Buff suggested that the explanation was to be sought 

 in a thermo-electric difference between the two electrodes. 



Sir William (Mr. Justice) Grove had shown moreover 

 that when a platinum wire is bent so that one end of it 

 stands in the tip of a flame, while the other is immersed 

 in the flame near its base, a current of electricity is set 

 up in the wire. This phenomenon might at first sight be 

 thought to agree with an observation of Hankel, that a 

 flame is " polarised " longitudinally ; that is to say, Hankel 

 found there is a difference of potential between the tip 

 and the base of a flame, and this difference of poten- 



