May si, 1883] 



NA TURE 



109 



other theories have been advanced, as for instance by 

 Grdnemann, Astr. Nachr., 1874-75, and the reason of 

 this is, I believe, that hitherto no direct proof had been 

 obtained demonstrating its true nature. 



But the experiments at Luosmavaara in iSyi, and at 

 OrcUuniuri and Pietarintunturi in 1882, clearly and un- 

 deniably prove that the aurora borealis is an electric 

 phenomenon. 



The science of the physical conditions of the globe has 

 hitherto, particularly as regards the electric and magnetic 

 ones, simply advanced by observing the effects of these great 

 forces of nature, without however any successful atte npt 

 having ever been made to influence or call them forth 

 either directly or indirectly. My experiments now, 

 however, prove that aurora borealis may be produced in 

 nature by a simple contrivance assisting the electric cur- 

 rent flowing from the atmosphere to the earth. And 

 although the efforts of man must always be limited in 

 comparison with the grand products of nature, the con- 

 clusions which may be drawn from the sime are not the 

 less instructive. 



In a question wherein the theoretical deductions, sup- 

 ported only by a few indirect proofs, have but slowly 

 advanced, absolute certainly has now been obtained, and 

 this result should induce future students of the aurora 

 borealis not to devote attention to the "light'' phenomenon 

 itself, but to the investigation of those wonderful forces 

 of nature the existence of which it so "lucidly " demon- 

 strates. We have, of course, much to learn from the 

 light also, but far more, I believe, from the electric forces 

 which create it. 



It is, however, far from my intention to insist that the 

 apparatus invented by me is the best or that the method 

 followed may not be improved on : still it has certainly 

 one advantage, viz. that of being effective. It is, of course, 

 evident that the drawbacks under which the experiments 

 suffered— as, for instance, weak wires and defective insu- 

 lators — must be remedied, and it appears to me that the 

 theory which is the basis of M. Mascart's insulator would 

 be particularly suited to the apparatus. The galvano- 

 meter should also be altered so as to consist of a great 

 number of well insulated coils, in order better to regulate 

 the deflexions, and the experiments should be made in 

 a warm room. As the electrometrical method hitherto 

 used gives only the electric tension at a certain point, it 

 would, it appears to me, form a good meter for measuring 

 the electric state of the surrounding atmosphere. The 

 galvanometer deflexions depend certainly on the electric 

 potential, as well as on the variable conducting power of 

 the air ; but it can, as will be seen from my experiments, 

 be measured and even divided by using a constant galvanic 

 element. The electric condition thus measured will give 

 us an idea of the strength of the electric current, which 

 in a certain place descends to the earth, and of the 

 electric changes which take place in the atmosphere. 



From the experiments with the terrestrial current de- 

 scribed above it seems very probable that the current is 

 closely related to the electricity in the auroral belt. The 

 terrestrial current is, as is generally known, related to the 

 magnetic variations, which is most conclusively shown by 

 Mr. Airy's curves (Phil. Trans., vol. exxxviii. p. 465). 

 In So lankyla disturbances of the terrestrial current were 

 always followed by a magnetic one. The exact result has 

 of course not yet been calculated, but a glance at the 

 figures returned is sufficient to show this. Mr. Airy's 

 researches have caused these questions: (1) Are the 

 variations in the terrestrial currents more numerous than 

 the corresponding magnetic ones? (2) Do the terrestrial 

 variations occur about half an hour from the correspond- 

 ing magnetic disturbances ? 



We have from the experience gained attempted to ex- 

 plain these peculiarities, viz. by the hypo hesis that the 

 earth forms, so to say, the core in a flexible bobbin, repre- 

 sented by the terrestrial current circulating around her. 



In the first place, many of the changes to which the ter- 

 restrial current is subject could not affect the magnetic 

 moment of the core, i.e. the earth ; and, in the second 

 place, the current acts directly on the instruments where- 

 by the magnetic variations are measured ; and in these 

 circumstances we must find the explanation of the first- 

 named peculiarity. With rega'd to the very remarkable 

 difference in time of about half an hour, this is the 

 exact time elapsing before the variations of the terres- 

 trial current can affect the magnetic moment of the earth. 

 It is, by the bye, only necessary to compare the duration 

 of induction currents produced in bobbins with different 

 iron cores, to observe that half an hour might well 

 pass before the current became perceptible, if the earth 

 constituted the core. In Polar regions the electric 

 current descending from the atmosphere to the earth may 

 also contribute to the variations which are measured by 

 our instruments. 



In accordance with this theory, therefore, the elec- 

 tricity which descends into the auroral belt is the primary 

 cause of the greatest part of the terrestrial current, and, 

 through this, of the many variations of the magnetic 

 elements. There are also others, as the diurnal changes 

 in the temperature on the earth's surface, but the chief 

 cause is, in my opinion, the electric current from the 

 atmosphere. 



In my belief, therefore, the possibility of explaining the 

 peculiarities of this phenomenon lies in a thorough and 

 complete knowledge of the current from the atmosphere. 

 Selim Lemstrom 

 Professor of the Helsingfors University 

 ( To be continued.') 



THE FLORA OF ANCIENT EGYPT 1 



THE discovery made bv Emil Biugsch Bey on July 6, 

 1881, in the vault of a king of the twentieth dynasty 

 is of the greatest importance to botany in consequence 

 of the large number of species of plants contained in the 

 offerings and funeral repasts and in the wreaths which 

 adorned the illustrious dead. Among them are several 

 which were not known to belong to ancient Egypt. I 

 have begun the studv of the remains of these plants 

 taken from the breasts of the most celebrated kings of 

 Egypt and of such inestimable value to science. Deputed 

 by Mr. Maspero to arrange these relics for the Egypto- 

 logical Museum of Boulak, I have classified them accord- 

 ing to the high personages for whom they were intended. 

 On the eight cardboards which I have the honour to send 

 you in the name of Mr. Maspero, you have a part of the 

 funeral wreaths belonging to Ramses II., Amenhotep I., 

 and Aahmes I. 



The wreaths of Ramses II. were renewed towards the 

 end of the twentieth dynasty (1 100 or 1200 B.C.), or at the 

 time of the twenty-first dynasty (1000 B.C.). The king of 

 that period, according to records inscribed on the coffins 

 and translated by Mr. Maspero. caused a new coffin to 

 be made for the great Ramses, the one in which he had 

 first been placed having been accidentally destroyed. In 

 this new coffin were several yards of wreaths, which Mr 

 Maspero handed to me. I have examined them all and 

 ascertained their composition. 



The wreaths of Ramses II. are formed of the leaves of 

 Mimusops Schimperi, Hochst, either folded or torn in 



. ■• Memoir on the Discovery at Deir-el-Bahari in Relation to the Ancient 

 Flora of Egypt." by G. Schweinfurth. [ this article, wr.tten m ( rench, was 



communicated to Sir Joseph D. H ooker bv I >r Schwemfurth. together with 

 a se of he wreaths flowers. &c . described thereto. These objects were 

 exhibited at the annual soiree of the Royal Society on the 25th ult and are 

 "wot view in No. 3 Museum. Royal Gardens, Kew. W.tn regard to the 

 Srthotrranhy of the names of the Egyptian longs, that employed by some of 

 AeSSg Egyptologists of this country has been ad .pted in th.s transla- 

 tion Tl'uf Amenhotep has been substituted for what looks like Amenhotpan 

 in Dr Schweinfurth". manuscript— W.B HEMSLEV.] 



See "La Trouvaille de fieir-elBahan." a. photogr. par ME 

 Brugsch. Texte par G. Maspero. (Le Calre : cher F. Macros et C.e.. 

 1881.) 



