196 



SCIENCE. 



[Vol. XI. No. 273 



ing of Harvard University, for researches in stellar photography. 

 On the same evening obituary memoirs were read, as follows ; by 

 Prof. G. F. Barker of the University of Pennsylvania, on the late 

 Prof. Henry Draper of New York ; by Prof. Comstock, on Prof. 

 Watson of the University of Michigan ; and by Mr. William Sellers 

 of Philadelphia, on Capt. James B. Eads. 



The president, Prof. O. C. Marsh, announced the death, since the 

 last meeting, of Dr. F. V. Hayden, an active member of the acad- 

 emy, and Prof. Asa Gray, an associate member. 



Largely attended receptions, at which many of the most distin- 

 guished people in Washington, both in official, scientific, and liter- 

 ary life, were invited to meet the members of the academy, were 

 given by Prof. Langley and Prof. Alexander Graham Bell, — the 

 former at the Smithsonian Institution, and the latter at Prof. Bell's 

 elegant Washington residence, which was opened for the first time 

 on that occasion since its injury by fire several months ago. A 

 number of dinners were also given during the week in honor of 

 distinguished members of the academy. 



The following is a full list of the papers entered : ' The Rota- 

 tion of the Sun,' by J. E. Oliver; 'The Foundations of Chemistry,' 

 by T. Sterry Hunt ; ' On an Improved Form of Quadrant Elec- 

 trometer, with Remarks upon its Use,' by T. C. Mendenhall ; ' On 

 the Vertebrate Fauna of the Puerco Series,' by E. D. Cope ; 

 ' Re-enforcement and Inhibition,' by H. P. Bowditch ; ' On Appar- 

 ent Elasticity produced in an Apparatus by the Pressure of the 

 Atmosphere, and the Bearing of the Phenomenon upon the Hypoth- 

 esis of Potential Energy,' by A. Graham Bell ; ' The Orbits of 

 Aerolites,' by H. A. Newton ; ' A Large Photographic Telescope,' 

 by E. C. Pickering; 'A New Method for the Biological Examina- 

 tion of Air, with a Description of an Aerobioscope,' by W. T. 

 Sedgwick and G. R. Tucker, presented by J. S. Billings ; ' Prelim- 

 inary Notice of the Object, Methods, and Results of a Systematic 

 Study of the Action of Definitely Related Chemical Compounds 

 upon Animals,' by Wolcott Gibbs and Hobart Amory Hare ; ' On 

 the Auditory Bones of the Batrachia,' by E. D. Cope ; ' The Orbit 

 of Hyperion,' by Ormond Stone, presented by S. Newcomb ; ' Map 

 of Connecticut River Region in Massachusetts,' by B. K. Emerson, 

 presented by J. W.Powell; 'Parallel Series in the Evolution of 

 Cephalopoda,' and 'Evolution of Cephalopoda in the Fauna of the 

 Lias,' by A. Hyatt; ' The Evidence of the Fossil Plants as to the 

 Age of the Potomac Formation,' by L. F. Ward, presented by J. 

 W. Powell ; ' Vision and Energy,' by S. P. Langley ; ' Report of 

 Progress in Spectrum Photography,' and 'Note on the Spectrum 

 of Carbon and its Existence in the Sun,' by H. A. Rowland ; ' On 

 the Constitution of the so-called Double Halogen Salts,' and 

 ' Studies on the Rate of Decomposition of the Bromides of the 

 Saturated Alcohol Radicals,' by Ira Remsen ; ' The Characteristics 

 of the Orders and Suborders of Fishes,' by Theo. Gill ; ' The 

 Serpent-Mound and its Surroundings,' by F. W. Putnam; 'The 

 Systematic Relations of Platypsyllus as determined by the Larva,' 

 by C. V. Riley, presented by Theo. Gill; ' On the Position of the 

 Nova of 1572, as determined by Tycho Brahe,' by C. H. F. Peters ; 

 ' Some Notes on the Laramie Groups,' and ' On the Structure and 

 Relations of Placoderm Fishes,' by J. S. Newberry. 



In selecting papers for notice in Science, those that admit of 

 statement in popular language have been taken rather than those 

 which in themselves are most important. Some of the latter are so 

 technical in their character as to be intelligible only to specialists. 

 The abstracts of papers are not given in the order in which they 

 were read. 



The Hypothesis of Potential Energy. 



The full title of Professor Alexander Graham Bell's paper read 

 at the morning session of Thursday was, ' On Apparent Elasticity 

 produced in an Apparatus by the Pressure of the Atmosphere, and 

 the Bearing of the Phenomenon upon the Hypothesis of Poten- 

 tial Energy.' Professor Bell showed to the academy an apparatus 

 that looked like the bellows of an accordion. It consisted of a 

 dozen or more sections, each eight inches long, four inches wide, 

 and two inches deep, connected by an air-tight fabric which sur- 

 rounded them and covered the outer portions of the end ones. A 

 tube was inserted in the middle one by which the air could be ex- 

 hausted. Before it was attached to the air-pump, the bellows was 



not elastic. Bent either to the one side or the other within cer- 

 tain limits, it would remain in the position in which it was placed. 

 But when the air was partially exhausted, if bent to one side or the 

 other, from the positiLin it assumed, it would spring back to its- 

 original position with considerable force. 



Of course, this elasticity was not due to potential energy, so called, 

 in the bellows, but to the pressure of the atmosphere upon the out- 

 side of it, holding the sections of it in close contact. An apparently 

 similar phenomenon in a piece of steel (as in a sword-blade, for in- 

 stance) is explained by saying that there is potential energy in the 

 steel. Professor Bell's experiment raises the question whether the 

 cause of the elasticity is in the steel itself, or outside of it ; whether, 

 in fact, there is any such thing as potential energy in matter, or if 

 its elasticity is not due to its surroundings. 



Professor Bell exhibited two very interesting modifications of his 

 apparatus. In the first the sections of the bellows were thinner on 

 one side than on the other ; so that, when the air was partially ex- 

 hausted, it would curl up in the form of a single section of a spiral 

 spring. When in that form, it resisted an effort either to coil it 

 tighter or to straighten it out, although it had none of that apparent 

 elasticity when filled with air under the normal pressure. In the 

 second, a large section was placed in the middle of the bellows, and 

 smaller ones each side of it. When the air was partially exhausted, 

 it was forcibly bent to form an arc of a circle, and a string attached 

 to each end, thus forming of it a bow, from which an arrow was 

 shot. 



An interesting discussion ensued after the presentation of Profes- 

 sor Bell's paper. Professor Simon Newcomb thought that Profes- 

 sor Bell's experiments suggested that molecular attraction, common- 

 ly called adhesion, may be due to an outward medium, but he did 

 not think it advances them at all on their way to the discovery of 

 this medium. He then defined the terms ' potential energy ' and 

 ' conservation of energy,' and explained what scientific men mear» 

 when they use them. 



Major J. W. Powell objected to the use of the phrase ' potential 

 energy ' as unscientific. As ordinarily employed, it is understood 

 to mean something that can do something, while really it is only 

 a name for something that we know nothing about. The thing 

 it applies to is nowhere, it does nothing, we know nothing about 

 it. The term as usually employed is misleading. 



Professor Newcomb replied that there is nothing unknown or in- 

 definite about the term ' potential energy,' and repeated his former 

 definition and explanation with several pertinent illustrations. 

 Professor Abbe probably suggested the cause of the divergence of 

 opinion between Professor Newcomb and Major Powell when he 

 said that the confusion arose because physicists give a definite 

 meaning to the term ' potential energy,' which naturalists do not. 



Serpent-Mound. 



A series of photographic views projected upon a screen made the 

 paper on ' Serpent-Mound and its Surroundings,' by Professor F. 

 W. Putnam of Harvard University, one of the most entertaining to 

 the non-scientific attendants at the meeting of the National Acad- 

 emy. This curious earthwork is in Adams County, O., on a bluff 

 about one hundred feet high, which forms one of the banks of 

 Brush Creek, about eighty miles from its mouth. The land upon 

 which it stands, with that surrounding it, comprising about seventy 

 acres, has been purchased by the Peabody Museum, and set aside 

 as a park. A gravel road has been built from the turnpike to 

 and into the grounds, a spring-house erected, and picnic-grounds 

 laid out. Although Professor Putnam began an examination of the 

 mound during visits to it several years ago, a systematic explora- 

 tion was not undertaken until last year ; and the paper presented 

 to the academy was a report of progress of that exploration. 



Briefly described, the mound consists of an oval earthwork about 

 four feet high and twenty feet across, enclosing a space eighty feet 

 long and twenty feet wide. The length of the structure on the 

 outside is one hundred and twenty feet, and its width sixty feet. 

 There is a little mound of stones within the enclosed space. Near 

 one end of this mound begins another of similar construction, 

 but having the form of a serpent. The jaws are extended as 

 though the snake was about to swallow the oval mound ; the head 



