i3§ 



NA TURE 



[Feb, 12, i i 



continuity established from cell to cell, but that the phenomenon 

 is of much wider t if not of universal occurrence" 



Kew. Sqitember 7 \V. T. Thiselton Dyer 



A Plea for the Experimental Investigation of some 

 Geological Problems 



The subject of terrestrial physics involves the study of such a 

 large number of phenomena that it is quite comprehensible that 

 any one investigator must devote himself to only one or two 

 branches of it at the most. The consequence of this is that from 

 time to time some section of this extensive field of research is for 

 a period neglected. Such is really the present state of experi- 

 mental geology, and especially that branch relating to movements 

 of the earth's surface. 



Disturbances perceptible at the terrestrial surface may be 

 looked upon as made up of three very distinct groups : first we 

 have actual upheaval or depression of comparatively large tracts 

 of land. Secondly, we have true earthquakes, which probably 

 are dependent upon a variety of circumstances, as, for instance, 

 the snapping of a rock stratum brought to the limit of its flexi- 

 bility in consequence of the first group of movements ; or the 

 formation and injection of fissures by igneous matter. Lastly, 

 there exists a series of small disturbances imperceptible to our 

 senses and even to ordinary instruments of earthquake measure- 

 ment, and only discoverable by special delicately constructed 

 apparatus. They seem to be dependent upon a variety of causes, 

 amongst which are those of the two former groups, together with 

 changes dependent upon or in relation with barometric pressure, 

 tidal action, temperature of the air, rainfall, &c. 



The upheaval or depression of our earth's surface is the very 

 basis of geological science, for it is in consequence of this that 

 rocks have been brought within the reach of investigation, and 

 that our globe has some dry ground upon which we can live, 

 instead of one continuous expanse of ocean. The changes of 

 level were suppo ed by the cataclysmic school of geologists to 

 occur suddenly, bringing about entirely new distributions of 

 land and water in a short period of time. Lyell, as the leader 

 of the unifirmists, laboured all his life to prove that these up- 

 heavals were in the main a slow and gradual process, extending 

 over long periods of time. One of this author's examples which 

 he brought forward in the argument with as much skill and force 

 as an accomplished counsel would have done in pleading a cause, 

 was the renowned (so-called) temple of Serapis at Pozzuoli. 

 This building wa. fir half a century the subject of almost in- 

 numerable books and pamphlets, some of which show a vast 

 amount of ingenuity. None perhaps were more elaborately 

 worked out than the volume of researches on the phenomena of 

 this building and the neighbouring coast from Gaeta, around the 

 whole gulf of that name, together with the Gulf of Naples, to 

 the Punta Campanella. The author there brings forward a large 

 amount of genuine evidence to show that during the last 2000 

 years the whole coast has been in a state of oscillation, so that 

 the relative change of level of the land and sea has been as much 

 a- \i m. So far as Niccolini's investigations were capable of 

 being carried out, abundant evidence showed that about the 

 second or third century B.C. the coast line commenced to 

 descend, and continued to do so gradually until the 10th or nth 

 centuries, when elevation took place for nearly 6 m., till in the 

 sixteenth century, when depression again set in. This depression 

 is now going on in a remarkably rapid manner. I have in my 

 possession an engraving of the temple of Serapis, in which the 

 base of the three columns stands on the upper antique pavement 

 of the building, which is perfectly dry. This is dated 1810. In 

 Niccolini's work is another drawing, made in 1845, in which 

 water had commenced to collect, so that it was necessary to 

 wade about. In 1879 a layer of earth of over a metre had been 

 spread over the floor to make access convenient, the standing 

 column being surrounded by brickwork cylinders, and standing in 

 water of over a metre in depth. The ground was then dry, but 

 from time to time when I visited the building I found puddles 

 commenced to collect, which at last grew so large and deep that 

 lately an additional layer of sea-sand has been added to further 

 raise the level. Similar variations have been observed in other 

 parts of both of the Mediterranean and Adriatic coasts of Italy, 

 which all seem to indicate that this geologically speaking young 

 peninsula has not-yet stopped growing. 



But if the coast-lines are altering, are we not justified in sup- 

 posing that the axial ridges of the Apennines are not doing soralso, 

 even in all probability to a far greater extent, though from the 



want of a fixed datum-line, such a the sua may afford, we are 

 unable to appreciate the amount of disturbance ? It is not likely 

 that this change of levels exceeds 50 m. in historic times in 

 Italy. 



If we even accept the recent reports from Spain as gross 

 exaggerations, we cannot well believe them to be pure inven- 

 tions when changes of 400 m. are spoken of, which could hardly 

 be asserted without some foundation of truth. 



Now, are we not bound in some way to investigate these 

 phenomena, which involve the very principles of geological 

 science ? It is strange, but true, that around the Gulfs of Naples 

 and Gaeta no instrument exists for registering the relative level 

 of the sea, nor do there exist any marks on rocks that are 

 officially looked after. During the earthquake of Ischia of 1883 

 it is not known whether any disturbance of the sea took place, 

 and we are perfectly ignorant of the rate and other characters in 

 the change of the relative levels of the land and sea. 



But putting aside this gradual elevation or subsidence, are we 

 not permitting to slip by one of the mo t remarkable examples of 

 quick elevation and depression which from the accounts that 

 now reach us are taking place in Spain ? Were the reports as to 

 changes of three and four hundred metres true, we should be 

 compelled, to a certain extent, to accept in part the teachings of 

 the cataclysmists, 



It seems regrettable that England, which is the mother country 

 of geology, should allow such an opportunity as the Spanish 

 peninsula now presents for the investigation of important ter- 

 restrial disturbances to slip by. Even if the earthquakes them- 

 selves are not studied, little expense of time or money would be 

 necessary to chronicle at least the principal phenomena now in 

 progress, which the Royal or some other Society might well 

 take up. H. J. Johnston-Lavis 



Iridescent Clouds 



The letters of Prof. Piazzi-Smyth and Mr. J. Edmund Clark 

 (vol. xxxi. p. 148^ on iridescent clouds, while interesting, do 

 not, if I mistake not, record any new phenomena. The descrip- 

 tions given agree very well with that of a phenomenon which I 

 have observed here several times, and which is described in 

 Herschel s "Meteorology," p. 225. Here the phenomenon \-. 

 usually seen before the approach of the monsoon, and is looked 

 upon as a sign of its being near at hand. Under these circum- 

 stances it can hardly be admitted that they have any connection 

 with the cloud glows of which so much have been written, and 

 which, as observed from the top of D:dabetta (S600 feet), are a^ 

 brilliant as ever when the atmosphere is sufficiently dry. 



It may perhaps still be of interest to some to know that 

 observations made on the spectrum of the sun when seen 

 through mists from the same hill-top, showed that the spectrum 

 of the "green sun" can be completely reproduced by super- 

 posing the spectra of sunlight passing through a mist and 

 through a thick layer of moist air ; and it is probable that all 

 cases in which the sun has been seen green can be thus- 

 explained. C. Michie Smith 



The Christian College, Madras, Januay 1 



Science Teaching in Schools 



1 N the discussion as to the teaching of science I have failed 

 to find any distinct expression of an element in the subject 

 which has for years seemed to me of the highest importance, and 

 to which I should like with your permission to call attention. 

 In those of our schools where science is taught it is almost 

 always taken up late in the boy's career, often when he is 

 passing from the lower to the upper school. This I feel sure is 

 a mistake. Think for a moment of the process of evolution 

 of that phenomenon — the English schoolboy. In too many ca-es 

 he passes through the first, second, and third forms of a school, 

 learning little more than the habit of diligent plodding, and 

 developing little more than the art of storing away an unheard- 

 of quantity of dry facts. He learns, for instance, page after 

 page of grammar rules ; he learns rules for making numerical 

 transformations ; he even learns in the same fashion answers to 

 questions that examiners are known to set for the purpose of 

 finding out whether the pupil has been intelligently taught ! 

 The habits so acquired are valuable, but they are acquired at the 

 risk of sacrificing the boy's freshness, and with the subjugation 

 of his habit of independent reasoning. After several years of 

 such training the herald of science comes forward with such a 



