ITor- v., NO. 1W

��aiii] below a moiinlaln, or within any other extended region. The difficult! in the way of utilizing the masses of lead is the extreme miDuteness of the at- traction exerted by any manageable mass. On the whole, however, the latter method. In the bands of Bailey, Keich, aud otbera, has been the more reliable of llie two. A few jears since, the late Professor Von Jolly of Munich undertook to measure the attrac- tion of a globe of lead about one metre in diametei', upon a weight Id the pan of a halanee. The arm of the balance was at a height of twenty-one metres over the leaden globe, and the pan which heid 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 atiraciloii Iras exerted only upon one wstght.

A modification of Jolly's method was recently de- scribed In a paper read before the Berlin academy of sciences, by Arthur Kiinig aad Franz Ricbarz. These gentlemen propose the following modiScation of the long suspension. They will cast a great block of lead in the shape of a parallelopiped. On the horiitontal surface of this block will be placed an ordinary bal- ance, Hie scales of which shall swing very near the surface. A vertical hole will be bored through the block, directly under the point of luspension of each scale of the balance; and a second pair of scale-puns will be suspended below the block by wires attached to the upper scale-pans, and passing tlirough tliese 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 ie to be measured will be placed, the one in the upper, and the other in the opposite, lower, pan of the «cales. The attraction of the block will make the lower one lighter, and the upper one heavier. The positions nrill then be changed by removing the weight in the lawer pan to the pan immedialely above It, and vice versa. Then the attraction of iho block will make heavier the weight which was before lighter, aad i>>eeiier8a,tltu9 causing a difference In ibe welgbts animiatlng to four times the attraction of the block.

It is proper to add that this welgblng method is subject to a good deal of criticism. So tar as we are aware, its original inventor was Mr. C. S, Peirce, who proposed to utilize the Ilooaac tunnel for the purpose, — to bore a hole from the surface of the earth verti- ctilly 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 aa to render the method Inapplicable, It is difficult to see how Ton Jolly's apparatus could Lave been free from the same difficulty. The attraction of hia leaden sphere could only have been one Rvc-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 eojiditions. With a block of any manageable size, the attraction by the method of Konig and Rlcharz will hardly reach a millionth part of the weight. Btlll the authors are making arrangements to execute their experiment, and physlcUlB will look with interest for lis result.

��The prebistoric studies iu Portugal of Ihc hite lamented Carlos Ribeiro have already been brought to our readers' notice {Science, Dee, 14. 1)^83). He was the leading spirit at the LisboD congress, as well aa its geueral secre- tary ; and his long illness dating Trom that time, and hia death, which took plac 1882, account for the delay in the appearanos of this long-expected olHcial re[>ovt. It has DOW been given to the world in the most satis- factory manner, with beautiful typography ondi ample il lustrations, under the charge of Sig. Delgado, who has succeeded to the position oC director of the Geological bureau of PortugaU The freshness of it, however, is somewhat Im- paired, owing to the fidl ri»umi of the pro- ceedings, that was given by Cartailhac in tha Maliriaux, November and December, IftJiO^ and by Professor Bellucci. at even great«Fi length, in L'archivio per I'antropologia, e l'«t nologia, vol. !ci. fasc. 3.

It was understood that the chief interest o this congress would centre about the di&cs sion of the first question proposed : " Are the ^^ any proofs of the existence of man in Portugal during the tertiary epoch?" Rii»eiro and f Portuguese geologists desired that foreign gv ologists and prehistoric archeologists shoald visit and thoroughly study at least one of tbi localities from which the supposed tertifti] flints had mainly come. All this was accont plished, and the results are already well koowoi Ati excursion (somewhat of the nature of 4 picnic) WHS made to ' the desert of Otta,' about thirty miles north of Lisbon, where Pffl feasor Rellucci of Perugia found in place, ia I miocene deposit, a fliut flake with a welUmarki ' bulb of percuasion.' This was seen by t eral witnesses before it was detached, and tq many experts was pronounced to be of uii| doubted human origin. To the writer, ho* ever, the engraved figure of it does not appeal entirely convincing. Dpon their return, tbl series of flint objects discovered in this locality by Ribeiro, during the past twenty yeara, waa submitted to the judgment of a commission of nine experts. Their report, and the discusmoc^ that ensued thereupon, developed a great dia* erence of opinion. Upon the geological quel tion all were in accord with the Portuguei _ geologists, that the locality was the shore of i miocene lake. In regard to the archeologioi

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