May 19, 1898] 



NATURE 



59 



That the mimics of these are, at any rate, relatively palatable, 

 and that the mimicry is commonly efifectual under natural con- 

 ditions. (4) That each bird has separately to acquire its 

 experience, and well remembers what it has learned. On the 

 whole, therefore, the theory of Wallace and Bates is supported 

 by the facts detailed in Mr. Finn's papers, so far as they deal 

 with birds (and with the one mammal used). Prof. Poulton''s 

 suggestion that animals may be forced by hunger to eat unpalat- 

 able forms is also more than confirmed by Mr. Finn's experi- 

 ments, as the unpalatable forms were commonly eaten without 

 the stimulus of actual hunger — generally, Mr. Finn adds, with- 

 out signs of dislike. 



In Bulletin No. 2 of the Blue Hill Meteorological Observ- 

 atory, Mr. H. H. Clayton gives some very interesting examples 

 of the diurnal changes in temperature and humidity at different 

 heights in the free air. The observations were made by means 

 of kites, and on two occasions these were maintained in the air 

 during a large part of twenty-four consecutive hours. The 

 results show that the diurnal variation of temperature was very 

 slight or had entirely disappeared at about 2300 feet, and that 

 the relative humidity curve at that height was exactly opposite 

 in phase to that recorded at lower levels ; the minimum humidity 

 was recorded at night, and the maximum during the day. The 

 records during the day show that to a certain height (which 

 varies under different conditions) the temperature in the lowest 

 stratum decreases with increase of altitude approximately at \°"j 

 per 330 feet. Above that height the air is suddenly found 

 warmer, and then the temperature decreases with increasing 

 height at a somewhat lower rate. During the night there is a 

 marked inversion of temperature between the ground and 600 

 to 1000 feet. Above that height the temperature decreases at a 

 fairly uniform rate. The experiments were made under the 

 superintendence of Mr. A. L. Rotch, the proprietor of the 

 observatory. 



The latest contribution to the question of the age of the earth 

 comes from Mr. J. G. Goodchild, of H.M. Geological Survey, 

 in the form of a presidential address delivered before the Royal 

 Physical Society of Edinburgh, and just published in the Society's 

 Proceedings (Session cxxvi. , 1896-97). Many geologists have 

 attempted to estimate the length of the interval between the 

 present time and the period when the oldest strata containing 

 fossils were laid down ; and " vague, indefinite, but unquestion- 

 ably vast beyond conception " have been the conclusions. Mr. 

 Goodchild passes in review certain changes which are known to 

 have taken place in the past, working backwards from the 

 Glacial Period, and estimates the time required for the formation 

 of the rocks of the various geological periods. He concludes 

 that ninety-three millions of years have elapsed since the com- 

 mencement of the Tertiary Period, and .seven hundred millions of 

 years since the commencement of the Cambrian Period. More- 

 over, the beginning of life upon the earth may be as much further 

 back from Cambrian times as Cambrian times are removed 

 from our own, so that the total estimate assumes tremendous 

 proportions. 



In the paper referred to in the preceding note, Mr. Goodchild 

 confines his attention to the purelygeological sideof the question of 

 the age of the earth, leaving the physicists to take up the discussion 

 and deal with it in the light of new facts and views. He suggests 

 in conclusion that the following points ne^d consideration : (i) 

 Is it certain that the whole of the dawnward increment of heat 

 within the earth is due to any vestige of the earth's original 

 heat ? If not, why may not part of it be due to the conversion 

 of the energy of motion arising from terrestrial undulation (set 

 up mainly by luni-solar gravitational energy) into the energy of 

 heat? (2) Is it certain thit radiant energy in general differs 

 from gravitational energy in operating only between two solid 

 NO. 1490, VOL. 58] 



bodies? If radiant energy acts only between any two nlateriaS 



bodies, how do we know that the radiant energy of the sun, or 

 the heat of the earth, is being dissipated into space at anything: 

 like the rate which is generally assumed to be the case i 



We learn from the Lancet that the use of Rontgen rays as a 

 means of certifying the existence of death' was demonstrated at 

 a recent meeting of the Biological Society of Paris. M. Bou- 

 garde showed three photographs of the thorax, two of them froin> 

 living persons and the third from a corpse, all taken by the 

 X-rays. In the two first the different thoracic organs and the 

 walls of the thorax itself exhibited a hazy outline, so that 

 their limits could not be exactly made out. This, of course, 

 was owing to the natural movements of the parts, the pulsations 

 of the heart and the great vessels, and the movements of the 

 diaphragm. Even when the subjects held their breath so as to 

 minimise movement as much as possible the outlines were still 

 hazy, and the outline of the diaphragm was seen as a shadow 

 varying in depth and extending over the ninth and tenth inter- 

 costal spaces. The heart and great vessels were seen to occupy 

 the centre of the chest as a dark oval mass, the shadow of which, 

 was dense in the centre, and gradually faded away towards the 

 periphery until the almost transparent lungs were reached. In. 

 the radiograph of the corpse, however, the appearance was 

 quite different, for all the organs had sharp and well-definedt 

 edges. 



The Proceedings of the Academy of Natural Sciences of 

 Philadelphia contains an account of the discovery of a complete 

 volcanic crater of Mesozoic age near Pottstown, Montgomery 

 County, Pennsylvania, by Mr. E. Goldsmith. The chief 

 interest of the paper centres round the microscopical examin- 

 ation of some varieties of de-vitrified obsidian and of gabbro- 

 phonolite. Some specimens of amygdaloid were obtained from: 

 a boring which showed remarkable fluidal texture even to the 

 unaided eye. Basaltic columns of exceptional size were 

 observed, the diameters of the six-sided sections measuring in 

 some cases ten, eleven, and even fifteen feet across. 



Mr. E. Goldsmith contributes an interesting note on the 

 petrification of fossil bones to the Proceedings of the Academy 

 of Natural Sciences of Philadelphia. In digging for human, 

 remains in the deposits of the Port Kennedy limestone quarry, 

 a fissure in the Silurian limestone on the Schuylkill River,. 

 Pennsylvania, it was found that many of the fossil bones 

 obtained "fell to a me.aly powder" when touched. Mr. 

 Goldsmith has subjected specimens in various stages of petri- 

 faction to analysis, and finds that the "bone meal " contains 

 little or no calcium phosphate, but that it consists essentially of 

 dolomite. It is supposed that the change is effected by carbon 

 dioxide in the water retained in the fissure, the phosphoric acid 

 being transferred and reunited with ferric oxide and alumina to 

 form vivianite (which was found in the neighbourhood), and 

 magnesia being taken up at the same time. 



The current number of the Annates de I'lnstititt Pasteur 

 contains the report for the past year of the anti-rabic inocu- 

 lations carried out in P.iris. No less thm 1521 persons under- 

 went the treatment, which is 213 in excess of the number 

 recorded for the year 1897. In all, eight deaths from rabies 

 occurred, two of which, however, took place during the course 

 of treatment and before it could have taken effect. In one case 

 a patient was admitted in April, and underwent the inoculations, 

 but succumbed to rabies in the middle of October. Out of the 

 total number of patients 175 were foreigners, and of the latter 

 Egypt contributed 2, Greece i, the United States I, Germany 

 8, Belgium 14, Switzerland n, British India 33 ; whilst England,, 

 as usual, far exceeds in its contribution that of any other nation,, 

 the substantial number of 83 being sent from this country. By far. 



