316 



SCIENCE. 



[Vol. IV., No. 



the passage of the wave-current propagating the tele- 

 phonic action was exactly similar to the sinking of 

 the heat-waves into the earth, treated by Fourier; 

 and by reasoning from the nature of that wave propa- 

 gation he concluded that the sound of a deep bass 

 voice could be heard farther than that of a high- 

 pitched voice. Mr. Lockwood said that experience 

 in ocean-cable telegraphy confirmed this. Professor 

 Carhart stated that Lord Rayleigh had from similar 

 considerations calculated the farthest distance at 

 which telephonic communication could be main- 

 tained in such a cable as the Atlantic cable, and 

 gives the extreme limit as twenty miles. This is 

 fully confirmed by experience, according to the testi- 

 mony of Messrs. Preece and Lockwood. 



Capt. O. E. Michaelis, of the Frankford arsenal, 

 read a paper in which he recommended the study of 

 the 'structural metals,' iron, copper, brass, etc., by 

 electrical or magnetic methods, with a view to ascer- 

 taining whether some such methods could not be de- 

 vised that should detect weaknesses not otherwise 

 to be discovered. 



A short discussion then took place, on the measure- 

 ment of large currents, in which there was nothing 

 particulary interesting brought out. 



Professor Rowland then took up the subject of 

 lightning protection, and gave a short development 

 of Maxwell's suggestion that the house should be 

 placed in a metallic cage. A house in a complete 

 metallic cage, one enclosing it below as well as above, 

 would be completely protected if the wires of the 

 cage were sufficiently good conductors. This fact 

 leads to the following considerations. Lightning- 

 rods should run down the four corners of the house 

 and across the angles of the roof, joining at the top, 

 thus forming the skeleton of a cage. If rods are 

 also run down the middle of the sides of the house, 

 or if, in a long building, two or three equidistant 

 rods are run down the sides and connected with the 



rods running across the roof, so much the better. 

 These rods must be well grounded, otherwise they 

 are of no use at all, and may be worse than useless; 

 for, suppose the gas-pipes running through the house 

 have good earth connections, the lightning will be 

 likely to leap from the rods to the gas-pipes, and so 

 cause destruction. The rods down the sides should 

 therefore be connected by rods running across under 

 the building, as well as by those over the roof ; and 

 the gas and water pipes, as well as all large masses of 

 metal in the building, should be connected with the 

 rods by good conductors. It is, of course, necessary 

 that the rods should be of good conducting material, 

 — solid, not hollow. As it is important that the rods 

 should have a large cross-section, the twisted forms 

 with large surface and very little mass of metal are 

 not good, as there is no use in the twisting, and the 

 most important thing is that there should be plenty 

 of metal to conduct. There is not the slightest 

 necessity for insulating a lightning-rod : the safety 

 of a building depends only on its being easier for the 

 lightning to go around it than to go through it. Of 

 course, from the cage of rods above described, small 

 rods bearing points are to rise at different points on 

 the roof. How high these should be, or how close 

 together, is not very well determined. It is con- 

 sidered by some, that a rod protects the space in- 

 cluded in the cone whose height is that of the rod, 

 and the radius of whose base is also equal to the 

 length of the rod. Others think that a space is 

 protected equal to the cone whose height is that 

 of the rod, and whose base has a radius of twice that 

 amount. 



The time for adjournment having come, the con- 

 ference adjourned, subject to the call of the chair- 

 man, Professor Rowland, who is also president of the 

 commission. 



It is possible that there may be another session in 

 Philadelphia about the close of November. 



BRITISH ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. 



PROCEEDINGS OF THE SECTION OF 

 ANTHROPOLOGY. 



The admirable survey of the progress of anthro- 

 pological science, comprised in the address made by 

 Dr. Tylor as president of the section, was listened to 

 with great satisfaction by the members. In this as- 

 sociation, as in the American, anthropology has been 

 late in finding the recognition which its importance 

 as a science deserves. Heretofore it has been treated 

 as a department of the biological section. As the 

 communications have gradually taken a wider range, 

 and become more numerous, it was found that this 

 subordinate status was inconvenient. At the present 

 meeting, anthropology for the first time takes the 

 rank of a section, and with a fortunate choice of 

 officers, — the vice-presidents being Professors Boyd 

 Dawkins and Dr. Daniel Wilson, and the secretaries 



Messrs. G. W. Bloxam (recorder), Rev. J. "Campbell,. 

 Walter Hurst, and J. M. P. Lemoine. 



Among the papers which attracted most attention 

 may be ranked that of Professor Boyd Dawkins, on 

 the range of the Eskimo in space and time. In this 

 paper Professor Dawkins again urged with much in- 

 genuity and force his well-known opinions as to the 

 probability that the Eskimos are the survivors of the 

 prehistoric race known in Europe as the ' cave- 

 dwellers.' The- Eskimos are found along the Arctic 

 Ocean, from Labrador and Greenland to the west 

 coast, and thence extending into Asia. Everywhere 

 they appear to be a receding race, gradually retreat- 

 ing northward as they are pressed by stronger and 

 more warlike tribes, — in America by the Indians, in 

 Asia by the Mongols. The researches of Mr. Dall 

 had produced evidence that they formerly dwelt on 

 the west coast of America, far south of their present 



