April 2 1, iS8i] 



NA TURK 



583 



Godard, Director of the Ecole Monge in Paris, who has 

 brought twenty of the pupils with him. M. Fau, 

 Attorney-General of Algiers, is the President, and two 

 papers are announced for to-day : — One by M. Robert, 

 on the Humanitarian and Pedagogic Ideas of Jean 

 Comimiac (1572- 1670) ; the other by M. Berdelle, on the 

 Employment of Colours as a Means of Retaining in the 

 Mind certain given Numbers. 



An excellent geological map of Algiers to the scale of 

 I in 800,000 has recently been completed, and the forma- 

 tion of it has led to the simultaneous observation of 

 various facts connected with the physical geography of 

 the Central Sahara. A map of the proposed interior sea of 

 the Sahara has also been prepared, and the Trans-Sahara 

 Railway is spoken of as more than a probability. But 

 we very much doubt if this can ever be a success. If it 

 connected flourishing towns or portions of territory in 

 which great cities are ever likely to be established, as in 

 the case of the new American railways, there would be 

 some hope for it. As it is, however over-populated the 

 world may become, there is no likelihood of the forma- 

 tion of settlements in the heart of an unhealthy tropical 

 region. G. F. Rodwell 



MR. DARWIN ON VIVISECTION 



FROM the Times we reproduce the following letter 

 addressed by Mr. Darwin to Prof. Holmgren of 

 Upsala, in answer to a request for an expression of his 

 opinion on the question of the right to make experiments 

 on living animals for scientific purposes — a question 

 which is now being much discussed in Sweden : — 



"Down, Beckenham, April 14, 18S1 

 " Dear Sir, — In answer to your courteous letter of 

 April 7 1 have no objection to express my opinion with 

 respect to the right of experimenting on living animals. 

 I use this latter expression as more correct and compre- 

 hensive than that of vivisection. You are at liberty to 

 make any use of this letter which you may think fit, but 

 if published I should wish the whole to appear. I have 

 all my life been a strong advocate for humanity to animals, 

 and have done what I could in my writings to enforce this 

 duty. Several years ago, when the agitation against 

 physiologists commenced in England, it was asserted 

 that inhumanity was here practised and useless suffering 

 caused to animals ; and I was led to think that it might be 

 advisable to have an .Act of Parliament on the subject. I 

 then took an active part in trying to get a Bill passed, 

 such as would have removed all just cause of complaint, 

 and at the same time have left physiologists free to pursue 

 their researches — a Bill very different from the Act which 

 has since been passed. It is right to add that the inves- 

 tigation of the matter by a Royal Commission proved 

 that the accusations made against our English physio- 

 logists were false. From all that I have heard however 

 I fear that in some parts of Europe little regard is paid 

 to the sufferings of animals, and if this be the case I 

 should be glad to hear of legislation against inhumanity 

 in any such country. On the other hand I know that 

 physiology cannot possibly progress except by means of 

 experiments on living animals, and I feel the deepest 

 conviction that he who retards the progress of physiology 

 commi.s a crime against mankind. .Any one who 

 remembers, as I can, the state of this science half a 

 century ago must admit that it has made immense 

 progress, and it is now progressing at an ever-increasing 

 rate. 



" What improvements in medical practice may be 

 directly attributed to physiological research is a question 

 which can be properly discussed only by those physio- 

 logists and medical practitioners who have studied the 

 history of their subjects ; but, as far as 1 can learn, the 

 benefits are already great. However this maybe, no one. 



unless he is grossly ignorant of what science has done 

 for mankind, can entertain any doubt of the incalculable 

 benefits which will hereafter be derived from physiology, 

 not only by man, but by the lower animals. Look, for 

 instance, at Pasteur's results in modifying the germs of 

 the most malignant diseases, from which, as it so happens, 

 animals will in the first place receive more relief than 

 man. Let it be remembered how many lives and what a 

 fearful amount of suffering have been saved by the know- 

 ledge gained of parasitic worms through the experiments 

 of Virchow and others on living animals. In the future 

 every one will be astonished at the ingratitude shown, at 

 least in England, to these benefactors of mankind. As 

 for myself, permit me to assure you that I honour, and 

 shall always honour, every one who advances the noble 

 science of physiology. 



" Dear sir, yours faithfully, 



" Charles Darwin 

 "To Prof. Holmgren" 



THE MAGNETIC SURVEY OF MISSOURI 



IN the summer of 1878 the writer began a magnetic 

 survey of the State of Missouri. The work of the 

 first summer was confined to the north-east part of the 

 State, and no points of interest were brought out. During 

 the summer of 1S79 the work was extended over the 

 western half of the State, and it was made apparent that 

 diversity of surface exerted a much more important 

 influence than had been suspected. The lines of equal 

 declination were found to bend very sharply upon entering 

 the large vallejs, and the needle showed a tendency to set 

 at right angles to the valleys. This tendency seemed to 

 be greatest when the general direction of the valley made 

 au angle of 45" with the wtirw;;/ position of the needle, or 

 roughly, when the valley runs north-east and south-west, 

 or north-west and south-east. This tendency seems to 

 be inappreciable when the valleys run north and south, 

 or east and west. 



In the report of 1878 (Trans. St. Louis Acad, of Sc, 

 vol. iv. No. I, p. 143) it was suggested that this might 

 result from the bending of the stream-lines of the earth- 

 current sheet, due to the greater conducting power of the 

 moist valleys. In order to settle this point, further 

 examination is necessary, and it is proposed to determine 

 the earth- currents at a number of properly selected 

 stations. 



During the summer of 18S0 the work extended over 

 the south-eastern part of the State, where stili more im- 

 portant flexures of the isogoni:: lines were discovered. 

 Here, however, the position of the needle is probably 

 affected by the iron deposits, and the effect of contour is 

 studied to less advantage. At the close of 1880 observa- 

 tions had been made at forty-five stations. In order to 

 bring out the effect of contour, a relief map of the State 

 was constructed in wax, and was finally reproduced in 

 plaster. In this work use was made of the profiles of all 

 the railroads in the State, together with a list of over 300 

 elevations in the State, collected by Gannett. The iso- 

 gonic lines, which were first drawn upon an ordinary 

 map, in the usual manner, to represent the observations 

 thus far made, were then copied upon the relief map. In 

 doing this it became apparent at once that the forty-five 

 stations were wholly inadequnte, and that the isogonic 

 lines thus drawn are probably deserving of about the 

 same weight that a topographical map would deserve if 

 constructed from elevations at these stations. 



The Chart is made after an artotype, which will 

 accompany the third annual report in No. 2, vol. iv. 

 Trans. St. Louis Academy of Science. In the original 

 map the horizontal scale is twenty miles to the inch, the 

 elevations being exaggerated 200 times. This exaggera- 

 tion was necessary in order to bring out the form in the 

 photograph, since on a relief map, 1 50 feet square, the 



