90 



NATURE 



\Nov. 30, 1 87 1 



An earthquake look place in the beginning of October on the 

 Isthmus of Chiriqui near Panama. 



Dr. Robert Brown, in a communication on the "Interior 

 of Greenland," states that all the results of the attempted explo- 

 rations of the interior serve to show that this is one huge mcr 

 de glace, of which the outlets and overflow are the comparatively 

 small glaciers on the coast, though when compared with the 

 glacier system of the Alps, they are of gigantic size. The out- 

 skirting land is, to all intents and purposes, merely a circlet of 

 islands of greater or less extent. There are, in all probability, 

 no mountains in the interior — only a high plateau, from which 

 the unbroken ice is shed on either side to the east and west, the 

 greater slope being toward the west. No mountains have been 

 seen in the interior, the prospect being generally bounded by a 

 dim, icy horizon. Dr. Brown considers Greenland susceptible of 

 being crossed from side to side with dog or other sledges, pro- 

 vided the party start under experienced guides, and sufficiently 

 early in the year. 



Occasional glimpses of pre-historic times are afforded to us. 

 One of the Indian papers records the deeds of a mad elephant, 

 which made its way from the Rewah territory into the Mundla 

 district. The first day it attacked the village of Tarraj, when 

 the inhabitants took refuge on the roofs, but it killed a woman 

 and child. The next night it went to the village of Mauzah and 

 killed a boy. Two days after it killed a woman at Barbashore, 

 and on the following night added to the number a man and 

 woman at Kamaria. Thence it made its way to Donoria, and 

 the villagers tried to escape, but two old women met their 

 death, and another was trampled on and seriously injured. Its 

 next stage was Manori, destroying a woman and two children, 

 and so to Karbah. Here it snitched a baby from the mother's arms 

 and killed it, and in the evening succeeded in killing a man in the 

 same place. The next night a man was killed at Nigheri, and 

 on that following another at Banu. On the 7th February it met 

 with a check in passing the Ramgurgh Tahsil, where it was fired 

 on, and r.:treated to Bijori, taking revenge by killing a man and 

 a boy. On the Sth it surprised a party of villagers in the jungle, 

 who had escaped from Nanda, again taking a woman's baby 

 from her arms and killing it. Tire next slaughter was of a man 

 at Belgaon and another at Belgara. It then visited .Sayla, the 

 villagers making their escape, except one boy, who was caught 

 by it, but only rolled about for fun, but the elephant went into 

 the village and pulled down several houses. By the 15th he was 

 at Mohari, and injured a man and woman by rolling them about 

 without killing them. On the ig'h it killed one man and 

 wounded another at Naraingunj. By this time a party was got 

 together to resist it, about three weeks having elapsed, and the 

 animal was driven across the river Nerbudda and into the jungle 

 of a hill, but from which the force was inadequate to dislodge it. 

 In three weeks it drove the people out of many villages, killing 

 twenty-one persons, wounding others, and ravaging the country. 

 It is alleged to have devoured five of its victims. The above 

 recital of what took place in a relatively settled country, gives 

 colour to the legends of Hercules and Theseus. In this case 

 nothing is said of the destruction of crops which must have 

 taken place. 



An improvement in the apparatus attached to fire-engines has 

 been proposed by Mr. Prosser in the form of a spreading fire- 

 nozzle, the object of which is, by means of a number of moveable 

 as well as fixed fingers so to direct the jet of water that it shall 

 divide it into a more or less fine spray. The water is thus 

 economised, and instead of a large proportion running off after 

 scarcely coming into contact with the burning material, every 

 drop, falling in the form of a conical shower of rain, performs 

 its part towards extinguishing the fire. 



COLDING ON THE LAWS OF CURRENTS 

 IN ORDINARY CONDUITS AND IN THE 

 SEA 



II. 

 "PORCHHAMMER has filled up that gap by his researches 

 ■'■ upon the water of the ocean ; for we can now, by the help 

 of his results and of the temperatures, ascertain pretty exactly the 

 specific weight of the water of the ocean in the principal seas of 

 the globe. Calculation has proved the correctness of Maury's 

 original notion, viz., that the density of the water of the ocean 

 is least at the equator, and increases with tolerable regularity in 

 proportion as we advance towards the north and towards the 

 south. The water of the Atlantic seems to be of the greatest 

 density at about 60'^ N. latitude to the south and south-east of 

 Greenland. If we take this density as unity, the specific weight 

 of the water of the sea will on an average be represented by the 

 following numbers : — ■ 



Norther 

 Between 60° 



Hew 



lid 70" lati- 

 tude in Davis Straits 



About 60° latitude in the 

 Atlantic ...... 



Between 50° and 60° lati- 

 tude in the Atlantic . . 



Between 40° and 50° lati- 

 tude in the Atlantic . . 



Between 23° and 40° lati- 

 tude in the Atlantic . . 



Between o' and 23° lati- 

 tude in the Atlantic . . 



09966 



Southern Hemispheue 



In the Cold Currents of 



Cape Horn 0*9990 



In the Atlantic .... 09984 



In the Atla 



Of these the former, those of the Northern Hemisphere, are 

 most to be depended on, because the observations there have 

 been most numerous. 



It will be seen by this table that the density of the water 

 of the ocean increases along with the latitude, and in almost 

 the same proportion both north and south of the equator. But 

 Forchhammer has also determined the saltness of the sea at various 

 depths, and has found that it decreases in very slow proportion 

 with the increase of the depth. It we start from this fact, 

 taking account at the same time of the decrease of temperature 

 in proportion to the depth, we find the result to be that, at 500 

 fathoms below the surface, the density of the water of the sea 

 over the whole globe maybe considered as equal to i, the differ- 

 ence at any particular point being scarcely discernible. But 

 since the density of the water of the ocean at a depth of 3,000 

 feet is everywhere equal to I, and since at the surface it di- 

 minishes as we approach the equator, it is evident that the mass 

 of water underneath cannot be in equilibrium ; that if the surface 

 of the sea is more elevated between the tropics than under the 

 poles, and if we take the mean densities given above, at the 

 surface, and at the bottom of this liquid mass, we find that the 

 height of the surface of the sea above the level corresponding to 

 the density of I, ought to be nearly as follows : — 



Height between the Equator and the Tropics 6 '6 feet. 

 ,, ,, Tropics and 40° lat. . 4"2 ,, 



,, ,, 40° and 50° ,, 2*2 „ 



11 )> 50° and 60° ,, o'9 ,, 



,, at 60° ,, CO ,, 



,, between 60° and 70° ,, 30 ,, 



But a similar difference of level necessitates the formation of a 

 double surface-current passing from the equator to the two poles, 

 and that cannot take place without entailing a diminution of the 

 height of the water under the tropics, unless, indeed, there be an 

 equivalent afilux into the tropical seas. But if the level of the 

 water between the tropics be lower, the equilibrium of the under 

 strata will be destroyed, and there ought, consequently, to be a 

 submarine current which comes both from the north and the 

 south towards the equator. That there really exists a current in 

 that direction is a result of the circumstance that the temperature 

 of the sea decreases with the depth. 



Supposing then that there were no other forces in action, the 

 difference of level mentioned above, ought, as Maury at first ad- 

 mitted, to give rise to a surface-current from the equator to the 

 poles, and an under-current from the poles to the equator. 

 But these currents are enormously modified by the interven- 

 tion of other forces. The north-east trade-winds react against 

 this equatorial current of the northern hemisphere, exercising 

 upon the surface of the sea an oblique pressure, of which the 

 effect is greater than that of the difference of level. There re- 

 sults from this, reckoning from the 30° latitude, a rising of the 



