June i, 1888.] 



SCIENCE. 



261 



of the atmosphere without, no provision other than a moderately 

 strong- silk bag is required to prevent collapse. The inventor of the 

 proposed steel balloon hopes to gain greater lifting-power by using 

 a vacuum instead of gas, the absence of substance of any kind being- 

 lighter than even hydrogen-gas. But lie has to contend with the 

 tendency of the shell to collapse from the enormous pressure of the 

 atmospliere on the outside, which would not be counterbalanced 

 by any thing inside of it. 



The first question which presented itself was, how thick could 

 the metal of the shell be made, so that the buoyancy of the sphere, 

 which would be the most economical and the strongest form in 

 which it could be constructed, would just float it without lifting 

 any load ? The computations showed that the thickness of the 

 metal might be .000055 °f the radius of the shell. For example : if 

 the spherical shell was one hundred feet in diameter, the thickness 

 of the metal composing it could not be more than one-thirtieth of 

 an inch, provided it had no braces. If it was thicker, it would be 

 too heavy to float. Now, if it had no tendency to buckle, which of 

 course it would, the strength of the steel would have to be equiva- 

 lent to a resistance of more than 130.000 pounds to a square inch 

 to resist absolute crushing from the pressure of the air on a cross- 

 section of the metal. Steel of such high crushing-strength is not 

 •ductile, and cannot be made into such a shell. If the balloon is to be 

 braced inside, as the inventor suggests, just as much metal as would 

 be used in constructing the braces would have to be subtracted 

 from the thickness of that composing the shell. Of course, such a 

 shell would buckle long before the thickness of the metal of which 

 it was composed was reduced to .000055 °f 't^ radius. In other 

 words, it is mathematically demonstrated that no steel vacuum 

 balloon could be constructed which could raise even its own weight. 



This is an illustration of how intelligently Congress would be 

 likely to legislate on scientific matters unguided by intelligent scien- 

 tific advice. 



Death of Prof. E. B. Elliott. 



Prof. E. B. Elliott, actuary of the Treasury Department, died 

 suddenly of heart-disease on Thursday, May 24. He was nearly 

 sixty-five years of age, and had been in the employ of the govern- 

 ment since 1861. Professor Elliott was born in Sweden, IVIonroe 

 County, N.Y., was graduated from Hamilton College, and, after 

 teaching, became interested in the early development of telegraphy, 

 — an interest which he retained as long as he lived. His great 

 skill in making computations led him later to become the actuary 

 of a life-insurance company in Boston, which position he filled until 

 called to a similar office in the United States Sanitary Commission, 

 in 1861. 



In 1865 he was secretary of the commission for revising the 

 United States revenue laws, and in 1871 entered the Civil-Service 

 Reform Commission. His service as actuary of the Treasury De- 

 partment has covered a great amount of statistical and computation 

 work, which has been of the greatest value both to- the govern- 

 ment and to Congress. Professor Elliott was a member of the 

 American Association for the Advancement of Science, of which he 

 was chosen one of the vice-presidents in 1S82. He was always 

 very active, and presided over the section of economic science and 

 statistics. He was also a member of the Washington Philosophi- 

 cal Society, and, at a meeting reviewing the work of the last ten 

 years, it was reported that he had presented more papers to that 

 society in that period than any other member. He was a member 

 of the Cosmos Club and of many foreign learned societies. 



He has published a great number of papers on mathematical 

 physics and statistics, and in 1863 was a member of the Interna- 

 tional Statistical Congress in Berlin. He was greatly interested in 

 horology, and an active member of the American Horological 

 Society. At the time of his death he was engaged upon some im- 

 portant original investigations in that line. He was the first to 

 have a clock constructed with hands to indicate standard time in 

 the different divisions of this continent, long before any one hoped 

 that it would be so generally adopted in the United States. 



Professor Elliott prepared the tables of weights and measures in 

 the appendix of Webster's ' Counting-House Dictionary,' and also 

 those constructed on the metric system. He made his greatest 

 reputation by his many valuable statistical reports on coinage, 

 weights and measures, and on bonds. Some of these were pub- 



lished in the last ' United States Census Report,' especially in the 

 volume on vital statistics. He was a very genial and companion- 

 able man, rather contemplative, weighing carefully every new fact 

 brought to his attention, and striving to foresee its effects. He 

 will be greatly missed in Washington, and it will be very difficult 

 to fill his place. 



The Tape-Worm in Sheep. 



Over eighty-five per cent of the sheep examined in Colorado last 

 summer, according to a report made by Dr. Cooper Curtice to the 

 Biological Society at a recent meeting, were infected by a tape- 

 worm which is apparently indigenous to the Western country. 

 Similar parasites had been described in 1856 by Dr. K. JM. Diesing 

 from specimens obtained by Natesen from Brazilian deer ; but since 

 that time the species was apparently unnoticed. This species is 

 interesting, first, on account of its peculiar anatomy and the life- 

 history of the individual parasite; second, because of the history of 

 this species, which indicates it to be the first acquisition of a native 

 parasite by the sheep on this continent, and its subsequent distri- 

 bution in the United States; and, third, from an economic stand- 

 point, the discussion of it including a consideration of the disease 

 produced in sheep — the actual loss in death-rate, in wool and mut- 

 ton, due to the parasite — and of the problem of cure and preven- 

 tion of the disease. 



After describing the parasite, Dr, Curtice said that these tania 

 occur in the duodenum and gall-ducts of Western lambs and sheep. 

 They sometimes fill each. So tightly do they pack the gall-duct at 

 times, that they cannot be withdrawn without breaking them, and 

 the duct itself is distended by them. The smallest taenia, about 

 half a centimetre long, are always found in the duodenum. They 

 may be found from May to January : no observations were made in 

 the winter months. From the duodenum they pass into the gall- 

 duct, and occasionally into the pancreatic duct. The taenia are 

 usually found in assorted sizes, from the young to the adult, but all 

 may be nearly equal in size. From observations made upon a great 

 number of lambs, it seems that these parasites cannot mature in less 

 than six, or possibly ten months ; so that the tasnia in lambs would 

 not be capable of infecting other lambs until the former became 

 yearlings. No stages intermediate between the embryo escaping 

 from the parent segment and the taenia five rhillimetres long were 

 found. 



As this species has not been described in Europe, and has not 

 been noticed in eastern United States, it seems to have been ac- 

 quired by the sheep since their importation into this country. Span- 

 ish sheep were first imported about 1820. From the early impor- 

 tation of sheep into Mexico and lower California arose those im- 

 mense herds of mission sheep, and eventually the millions of sheep 

 now found in the West. These sheep are rapidly being interbred 

 with better grades of Eastern sheep ; but the Mexican sheep fur- 

 nished the material with which the sheep-men of the Plains began. 

 The history of the acquisition and distribution of this parasite is 

 believed, then, to be coincident with the history of these sheep since 

 their arrival in this country. This parasite, originally affecting deer 

 on this continent, is believed by Dr. Curtice to have become in- 

 grafted into sheep, animals with similar life-habits, and, through the 

 favorable conditions of ranching, to have spread rapidly with the 

 increase of the flocks. Its distribution is now from Oregon and 

 Wyoming southward, and Nebraska and Kansas westward. 



The disease they cause in sheep makes its appearance gradually, 

 and increases as the parasites grow. It is characterized by a hide- 

 bound, tucked-up condition of the lambs, which is indicative of lean, 

 ill-conditioned animals. Sheep may be apparently strong and 

 healthy, and still harbor a number of these parasites. The poorer 

 lambs generally die from exposure to inclement weather, or from 

 smothering by piling on top of each other in storms in their en- 

 deavors to keep warm. The actual loss by death among the lambs 

 is probably the least portion of it ; that occasioned by the dimin- 

 ished amount of fat, muscle, and wool, which, though small for 

 each animal, is constantly present from year to year, forms the 

 larger, and aggregates a total loss to the sheep-husbandry of the 

 Plains which is probably greater than that due to the scab-insect. 



As yet no effective medicinal remedy for the destruction of these 

 parasites has been discovered. Something may be done in the way 

 of prevention ; but, until the complete life-history of the taenia is 



