February 21, 1890.] 



SCIENCE. 



127 



12, 15;, 19, 22;-, etc., in the subseqiient rows. Thus m is a 

 member of an arithmetical series of which the common difference 

 is 21 for the first tlu-ee members, and 3i for all the I'est. On 

 calculating the values of the constant c from the equation c = 

 _^ 



for 55 of the elements, the numbers are all found to lie 



m + Vu 



between 6.0 and 7.2, with a mean value of 6.6. In by far the 

 majority of cases the value is much closer to the mean 6 6 than 

 is represented by the two extxeme limits : thus in 85 cases the 

 values lie between 6.4.5 and 6.75. If the number 0.6, therefore, 

 is adopted as the value of c, and the atomic weights of the ele- 

 ments are then calculated from the fornaila ^- = 66 (hi + s'v) , 

 the calculated atomic weights thus obtained approximate much 

 more closely to the experimental atomic weights than do the 

 numbere derived from an application of the atomic heat approxi- 

 mation of Duloug and Petit. The number 0.6 at once strikes one 

 as being remarl^ably near to the celebrated 6.4 of Dulong and 

 Petit, and Professor Carnelley draws the conclusion that there 

 must be a connection between the two. This assumption appears 

 to be supported by the following interesting facts. If we assume 

 c to represent the atomic heat, then atomic weight = atomic 

 heat X (m -|- +/■«)= atomic weight x specific heat x («i + 

 1 



Vv) ; or specific heat = 



On calculating the specific 



m + (/ V 



heats of the elements from this equation, they are found to agree 

 remarkably well with the experimental values, except in those 

 cases in which the observed specific heat is known to be ab- 

 normal. Again, Bettone has shown that the hardness of the ele- 

 ments is inversely proportional to their specific volumes. If this 

 be so, hardness = specific gravity. ^^^^^ on calculating the hard- 



6.6 {m +. \-'v) 

 ness from this formula, the numbers are again found to agree 

 very closely with the hardness experimentally determined by 

 Bettone. That the periodic law may therefore be approximately 

 expressed by a formula of the type A — c {m + \'v) appears 

 very probable, and that the number 6.0 is a very close approxi- 

 mation to the value of c appears also to be established. More- 

 over, the fact that m in the even series represents a whole num- 

 ber, while in the odd series it represents a whole number and a 

 half, corresponds to the well-known difference in chemical prop- 

 erties betsveen the members of these series ; and the assumption 

 that the common difference between the first tlu-ee values of m 

 is only Si, while between all the rest it is 3|, is borne out by 

 Mendeleeff's statement that the elements of the lithium and sodi- 

 um I'ows are more or less exceptional in their nature, and not 

 strictly comparable with the subsequent series. 



— The demand for fibre-machinery, so extensive of late years 

 in Mexico, is likely to be increased under more favorable fiscal 

 circumstances by the development on a large scale of the sisal 

 hemp industry of the Bahamas. Last year Sir Ambrose Shea, 

 governor of these islands, which are a natural continuation of 

 Florida, wrote to the London Times a powerful appeal that British 

 capitalists should undertake the cultivation in the Bahamas 

 of this rival to manila hemp. The demand for the latter long 

 ago outstripped the supply; and, to make good the deficiency, 

 fibre has been sought for in all parts of the world. The most 

 successful substitute of all, we learn from Engineering of Jan. 

 31, has been sisal, a wild hemp-plant indigenous to Central 

 America and the West Indies. Thanks to the prompt enter- 

 prise of Americans, the trade soon began to flourish in Yucatao, 

 where large tracts of waste lands are covered with sisal hemp. 

 Experience, however, soon revealed that ouly carefully selected 

 plants, properly cultivated, could produce fibre that would 

 stand the tests applied to good manila. It was found, more- 

 over, that the plant was stronger and more fibrous in the Ba- 

 hamas than in Mexico: and the result was, that in order to 

 render these islands the counterpart of the Manilas in pros- 

 perity, if possible, the authorities decided to grant an export 

 bounty of £4 13s. 4d. per ton on all sisal hemp grown in the 

 Bahamas. The effect of this encouragement has been to draw 

 English capital to the islands, where aiTangments are now 

 being made to plant ten thousand acres wijh this useful plant. 



Sisal is like an aloe in appearance, and has leaves about six 

 feet long. It grows wild on the poorest soils, sprouting freely 

 from a sucker, and in three years the leaves are ready for 

 plucking. For nearly twenty years it continues to furnish, 

 season after season, crojjs of these leaves, which are gathered 

 by coolies, placed in fibre-machines, and are baled ready for 

 export within a few hours of being plucked. Excessive drought 

 or rain having no effect on the plant, and no attention beyond 

 pruning being needed after the first year or two, the crop is 

 inexpensive to manage, and practically permanent for twenty 

 years, when the old plants are replaced by young ones. If the 

 energetic encouragement of the governor, and the liberal bounty 

 granted, cause the cultivation of the plant to be conducted on a 

 large scale, a fresh lease of prosperity will be conferred upon 

 the Bahamas, and the machinery trade, as well as the fibre one, 

 will benefit by the new' West Indian industi'y. 



— From a desire to verify his own researches as to the causes 

 of failing nutrition in aged organisms, Mr. C. A. Stevens offers 

 three cash prizes of $175, $125, and $100 for the best three 

 comparative demonstrations, by means of microscopical slides, 

 of the blood capillaries in young and in aged tissues, canine or 

 human. By young tissues (canine) are meant tissues from 

 animals between the ages of one and three years. By aged tissues 

 (canine) are meant tissues from animals not less than twelve 

 years of age. By young tissues (human) are meant tissues from 

 subjects between the ages of ten and twenty years. By aged tis- 

 sues (human) are meant tissues from subjects not less than sixty- 

 five years of age. While a preference will be given to demon- 

 strations from human tissues, it will be possible for work in 

 canine tissues to take the first, and indeed all, of the prizes. 

 But of two slides equally well done in all respects, one canine, 

 the other human, the latter will be given the preference. Ca- 

 nine tissues should be from large animals. Twelve slides from 

 young and twelve from aged tissues must be submitted by each 

 competitor, together with a full description of the subjects, 

 methods pursued, and every detail and circumstance which is 

 likely to throw light upon, or account for, any peculiarity. 

 The slides are for comparison as to the condition of capillary 

 circulation, the young with the old, and should be in numbered 

 pairs, or groups from the same kind of tissue. The term 

 "tissue" is used in a general sense; e.g., pulmonary tissue, 

 hepatic tissue, renal tissue, osseouj tissue, muscular tissue, 

 nerve tissue, alimentary tissue, etc. No particular schedule of 

 methods for injection or staining will be insisted upon, and no more 

 definite directions or explanations will be given. The slides, care- 

 fully packed and boxed, together with descriptive manuscript, can 

 be sent by mail. It is stipulated that the demonstrations which 

 receive the prizes shall become the property of Mr. Stevens, for 

 publication. All others will be returned, if desired. No 

 pseudonymes required. Accompany slides, in every case, with 

 (real) name and address. Unless of known reputation as a 

 biologist, a reference is respectfully solicited. Reservation ; no 

 award will be made unless work of at least ordinary merit is sub- 

 mitted. This offer is made on the first day of January, 1890, and 

 will remain open until the twentieth day of August, 1890. 

 Slides and manuscript will be examined and receipted for as soon 

 as received. The prizes will be adjudged on the first day of Octo- 

 ber, 1890. These nominal prizes are offered less in expectation 

 of results from the money as an agent than in the hope that 

 the offer may furnish a poiiit cVappui for really needed work. 

 Besides professional observers and students, there are in the 

 United States a large number of amateur microscopists of 

 acute vision and undoubted talent, who are at present playing 

 with microscopes as with toys, merely to see- the curious or 

 pretty things. The time has come to concentrate observation 

 upon the one proper object of biology; viz., the renovation 

 and prolongation of human life. Mr. Stevens's address is Nor- 

 way Lake, Me. 



— Herbert Ward, the African explorer, in collaboration with 

 D. D. Bid well, begins in the New York Ledger of March 1 a series 

 of articles descriptive of a canoe journey of twenty-five hundred 

 miles on the Upper Kongo. 



