218 



SCIENCE 



[Vol. V., No. 110. 



and below a mountain, or within any other extended 

 region. The difficulty in the way of utilizing the 

 masses of lead is the extreme minuteness of the at- 

 traction exerted by any manageable mass. On the 

 whole, however, the latter method, in the hands of 

 Bailey, Keich, and others, has been the more reliable 

 of the two. A few years since, the late Professor 

 Von Jolly of Munich undertook to measure the attrac- 

 tion of a globe of lead about one metre in diameter, 

 upon a weight in the pan of a balance. The arm of 

 the balance was at a height of twenty-one metres over 

 the leaden globe, and the pan which held the weight 

 was suspended by a wire of that length. It was bal- 

 anced by a weight in the other pan immediately below 

 the balance, so that the attraction was exerted only 

 upon one weight. 



A modification of Jolly's method was recently de- 

 scribed in a paper read before the Berlin academy of 

 sciences, by Arthur Kdnig and Franz Richarz. These 

 gentlemen propose the following modification of the 

 long suspension. They will cast a great block of lead 

 in the shape of a parallelopiped. On the horizontal 

 surface of this block will be placed an ordinary bal- 

 ance, the scales of which shall swing very near the 

 surface. A vertical hole will be bored through the 

 block, directly under the point of suspension of each 

 scale of the balance; and a second pair of scale-pans 

 will be suspended below the block by wires attached 

 to the upper scale-pans, and passing through these 

 openings. Thus the balance will consist of two pairs 

 of scale-pans, — one pair below, the other above, — 

 with the leaden mass between them. The masses 

 whose attraction is to be measured will be placed, the 

 one in the upper, and the other in the opposite, lower, 

 pan of the scales. The attraction of the block will 

 make the lower one lighter, and the upper one heavier. 

 The positions will then be changed by removing the 

 weight in the lower pan to the pan immediately above 

 it, and vice versa. Then the attraction of the block 

 will make heavier the weight which was before lighter, 

 and vice versa, thus causing a difference in the weights 

 amounting to four times the attraction of the block. 



It is proper to add that this weighing method is 

 subject to a good deal of criticism. So far as we are 

 aware, its original inventor was Mr. C. S. Peirce, who 

 proposed to utilize the Hoosac tunnel for the purpose, 

 — to bore a hole from the surface of the earth verti- 

 cally to the tunnel, and use it for the passage of a 

 wire to hold a weight supported by a balance at the 

 surface. It was found, however, that the air-cur- 

 rents, and other sources of disturbances, were such 

 as to render the method inapplicable. It is difficult 

 to see how Von Jolly's apparatus could have been 

 free from the same difficulty. The attraction of his 

 leaden sphere could only have been one five-millionth 

 part of the weight, — a fraction which is about the 

 extreme limit with which it is possible to effect a 

 weighing under the most favorable conditions. With 

 a block of any manageable size, the attraction by the 

 method of Konig and Richarz will hardly reach a 

 millionth part of the weight. Still the authors are 

 making arrangements to execute their experiment, 

 and physicists will look with interest for its result. 



THE PREHISTORIC CONGRESS AT 

 LISBON. 



The prehistoric studies in Portugal of the 

 late lamented Carlos Ribeiro have already been 

 brought to our readers' notice (Science, Dec. 

 14, 1883). He was the leading spirit at the 

 Lisbon congress, as well as its general secre- 

 tary ; and his long illness dating from that 

 time, and his death, which took place Nov. 13, 

 1882, account for the delay in the appearance 

 of this long-expected official report. It has 

 now been given to the world in the most satis- 

 factory manner, with beautiful typography and 

 ample illustrations, under the charge of Sig. 

 Delgado, who has succeeded to the position of 

 director of the Geological bureau of Portugal. 

 The freshness of it, however, is somewhat im- 

 paired, owing to the full resume of the pro- 

 ceedings, that was given by Cartailhac in the 

 Materiaux, November and December, 1880, 

 and by Professor Bellucci, at even greater 

 length, in Uarcliivio per Vantropologia, e Vet- 

 nologia, vol. xi. fasc. 3. 



It was understood that the chief interest of 

 this congress would centre about the discus- 

 sion of the first question proposed : ' ' Are there 

 an}^ proofs of the existence of man in Portugal 

 during the tertiary epoch ? " Ribeiro and the 

 Portuguese geologists desired that foreign ge- 

 ologists and prehistoric archeologists should 

 visit and thoroughly study at least one of the 

 localities from which the supposed tertiary 

 flints had mainly come. All this was accom- 

 plished, and the results are already well known. 

 An excursion (somewhat of the nature of a 

 picnic) was made to ' the desert of Otta,' 

 about thirty miles north of Lisbon, where Pro- 

 fessor Bellucci of Perugia found in place, in a 

 miocene deposit, a flint flake with a well-marked 

 ' bulb of percussion.' This was seen by sev- 

 eral witnesses before it was detached, and by 

 many experts was pronounced to be of un- 

 doubted human origin. To the writer, how- 

 ever, the engraved figure of it does not appear 

 entirely convincing. Upon their return, the 

 series of flint objects discovered in this locality 

 by Ribeiro, during the past twenty years, was 

 submitted to the judgment of a commission of 

 nine experts. Their report, and the discussion 

 that ensued thereupon, developed a great dif- 

 erence of opinion. Upon the geological ques- 

 tion all were in accord with the Portuguese 

 geologists, that the locality was the shore of a 

 miocene lake. In regard to the archeological 



Congres international d' anthropologic et d'archeologie pre- 

 historiques. Compte rendu de la neuvieme session a Lisbonne, 

 1880. Lisbonne, Typographie de VAcademie royale des sci- 

 ences, 1884. 49 + 723 p., 44 pi. 8°. 



