September i, 1923] 



NA TURE 



;4i 



line joining the nuclei, the length of the base being 

 i-ioo7a„. 



It is generally admitted that while the Bohr atom 

 is able to account quantitatively for the phenomena 

 issociated with it, the Bohr molecule is far from 

 satisfactory. If a " quantum force " act between 

 each pair of the four electric charges which constitute 

 the neutral molecule, it is possible to replace Bohr's 

 model of the hydrogen molecule by a model with 

 the electrons at rest relatively to the hydrogen nuclei. 

 Various configurations of equilibrium are theoretically 

 possible, but not all of these are stable. The most 

 stable configuration, from the point of view of 

 ordinary statics, appears to be that in which the 

 nuclei and electrons are situated at the corners of a 

 square, with the nuclei at the ends of one diagonal 

 and the electrons at the ends of the other. The 

 length of a diagonal is i-6407a„. When n—\, the 

 length of a diagonal is 0-871 Angstrom units, and this 

 case is illustrated in Fig. i (c) . Another configuration 

 agrees exactly with that obtained from Bohr's theory 

 and is shown in Fig. i (6), but the electrons are now at 

 rest instead of in circular motion. In a third con- 

 figuration, the positions of the charges are similar 

 but the positions of the black and white balls must 

 be interchanged. 



It is possible that such configurations might exist 

 for a time side by side, and such a possibility is 

 suggestive in connexion with the varied values some- 

 times found in determinations of ionisation potentials. 

 When collisions between gaseous molecules are taken 

 into consideration, it is not easy to say what would 

 be the most probable configuration in the final dis- 

 tribution. It is certainly instructive to find such a 

 possibility of different configurations in the case of 

 the simple hydrogen molecule, and points to the 

 necessity of guarding against too rigid an interpreta- 

 tion of the phrase " gaseous molecule " in speaking 

 of more complex gases, whether elements or com- 

 pounds. 



The actual existence of a positively charged hydrogen 

 molecule is demonstrated in experiments by Sir J. J- 

 Thomson and Dr. Aston. On the present hypothesis 

 a stable configuration is obtained by placing the 



single electron at the middle point of the line joining 

 the atomic nuclei. In the one-quantum state the dis- 

 tance between the nuclei is 1-239 A.U., as in Fig. i {d). 

 The ionisation potential for the complete dissociation 

 of the charged molecule is 17-34 volts as against 

 11-87 volts on Bohr's theory. This should serve to 

 discriminate between the two theories. 



A possible configuration may be suggested for a 

 neutral triatomic hydrogen molecule, Hg, in which 

 the nuclei and electrons are situated at alternate 

 corners of a regular hexagon (length of side, 0-625 A.U.) . 



Some of the more important numerical data are 

 collected in the following table ; full details will 

 appear in a paper in course of publication in the 

 Proceedings of the Royal Society of Edinburgh. 



Table I. 



e=angle between the line joining nucleus and electron and the line joining 



nuclei. 

 di=distance between the nuclei in the one-quantum state. 

 Ii = moment of inertia in C.G.S. units for the one-quantum state. 

 W=work required for complete dissociation expressed in equivalent volts. 



The ionisation potentials calculated from the values 

 of W in the table are in moderately good agreement 

 with the experimental results. A more exacting test 

 of the accuracy of such a model is to be expected from 

 a study of the wave-lengths of lines in the secondary 

 spectrum of hydrogen. Even though the numerical 

 values quoted may have to be modified, it may be 

 claimed that it is now possible to postulate a hydrogen 

 molecule in which the electrons are at rest instead 

 of in orbital motion. It is obvious that the principles 

 here employed may be applied to more complex 

 atomic and molecular systems. 



The Liverpool Observatory (Bidston). 



AFTER a career of eighty years, during which the 

 Liverpool Observatory has fulfilled the purpose 

 for which it was designed, the Mersey Docks and 

 Harbour Board, which is responsible for its support 

 and management, has decided that the time has 

 arrived when the usefulness of the institution might 

 lie increased by directing its energies into channels 

 additional to those originally contemplated. It may 

 be recalled that the chief objects sought in establish- 

 ing an Observatorv in Liverpool were the communica- 

 tion of accurate time to the Port and the rating of 

 chronometers. The action of the British Association 

 at the Liverpool meeting in 1837 contributed largely 

 to the adoption of the necessary measures ; the meet- 

 ing in 1923 might give similar encouraging support to 

 the widened programme now under consideration. 



The Mersey Docks and Harbour Board considers 

 that the facilities which the Observatory affords for 

 the advancement of knowledge and diffusion of 

 science and learning might be increased if a closer 

 union could be established with the University. As a 

 preliminary measure, it is suggested that the future 

 administration and working of the Observatory'- may 

 be advantageously entrusted to a joint committee of 

 the Board and University, each nominating five 

 members. This joint committee has now been 



NO. 2809, VOL. 112] 



appointed, the Board's representatives being Mr. 

 C. Livingston, Mr. H. F. Fernie, Col. H. Concanon, 

 the Marine Surveyor and Water Bailiff, the director 

 of the Observatory; and the University nominees, 

 Mr. C. Booth, Prof. Johnstone, Prof. Proudman, and 

 Prof. Wilberforce. 



The Dock Board and the University are actuated 

 by a desire to effect an intimate connexion between 

 the recently constituted Tidal Institute, the Obser- 

 vatory, and the department of the Marine Surveyor. 

 The meteorological statistics collected by the Observa- 

 tory are useful in extending the researches of the 

 Institute in particular directions, while the tidal 

 measurements conducted by the Marine Surveyor 

 afford the necessary means for testing the accuracy of 

 prediction. This closer co-operation has the addi- 

 tional advantage of removing the inconvenience of 

 overlapping. 



By utilising the existing establishment as the 

 nucleus of a geophysical observatory, teaching could 

 be combined with research — an extension which is 

 not only feasible but eminently desirable. None of 

 the past activities need be abandoned. The scientific 

 centre would be maintained unimpaired, and its 

 traditions continued. The greater activity exhibited, 

 and the execution of an enlarged programme arranged 



