SCIENCE. 



167 



in conjunction with the negative or lower end of the needle. 

 This is continued irom high to low and from low to high 

 water and from day to day, the result being recorded as 

 read off. The mechanical difficulties in the construction of 

 the machine are very great, but not considered insuperable. 



ON THE DEFICIENCIES OF METEOROLOGICAL 

 WORK IN DATA OF VALUE TO AGRICUL- 

 TURE. AND MEANS FOR SUPPLYING THEM. 



By William McMurtrie. 



Meteorological records, as they are and have been and 

 are being made, are deficient in many of those data which 

 have the most important influence upon farm crops. Tem- 

 peratures are recorded, but they are always observed in the 

 shade. Rainfall is given, but often in such a way as to ren- 

 der its record of no value in the study of the development 

 and condition of crops, because no indication is given as to 

 the way in which it is distributed ; light being of little im- 

 portance to meteorologists generally, while it is one of the 

 most potent factors in the development of vegetable and 

 animal life, has been almost completely ignored. Late in- 

 vestigations have proven conclusively the importance of the 

 tension of atmospheric electricity upon vegetation, and it 

 should be regularly observed and recorded. In fact, me- 

 teorologists have principally confined themselves to the re- 

 cord and study of such conditions as enable them to predict 

 the approach and occurrence of storms, thus looking more 

 to the commercial than to the cultural side. Gasparin was 

 the first to call attention to the importance of the relations 

 of Meteorology to agriculture, and he has had at least two 

 active followers — Quetelet in Belgium, and Marie Davy in 

 France. Through the instrumentality of the latter there 

 has been established, near Paris, an observatory of Agricul- 

 tural Meteorology, where observation and record of all the 

 conditions above named is made. The results already ob- 

 tained have shown great practical value, and worthy of the 

 means and labor required in securing them. In this coun- 

 try we have nothing similar to it. Our Signal Bureau, as 

 nearly perfect as may be for the purposes for which it was 

 designed, is devoted to the record and study of those ob- 

 servations as will render possible the prediction of future 

 conditions which may affect human affairs, than such as may 

 influence the development of crops. Besides this, the num- 

 ber of stations at which observations are made in this coun- 

 try is too limited, being not over 800, while for agricultural 

 work 3,000 would not be excessive. Additional work 

 should, therefore, be carried on, and observations at a larger 

 number of stations made and recorded, to be discussed in 

 connection with the records of observations made upon the 

 condition of the crops. The nature of the work is such that 

 it should be undertaken by the Department of Agriculture, 

 and the organization of the latter with the 2,300 reporters it 

 already employed would be well adapted to it. Fortunate- 

 ly, General Le Due, the Commissioner of agriculture, is in 

 favor of the establishment of such work in the Department, 

 but will require congressional support to enable him to do 

 so. The plan of work suggested by the author is as follows : 

 1. The establishment of a system of observation and record 

 among the reporters of the Department of Agriculture, and 

 others whose co-operation could be secured throughout the 

 United States and Territories, with instructions to observ- 

 ers to keep careful records of the conditions of atmospheric 

 pressure, temperature in its various relations, relative hu- 

 midity, evaporation of moisture, winds, light, tension of 

 atmospheric electricity, occurrence of dews, fogs and frosts, 

 and report them at stated intervals of time to the Depart- 

 ment for consideration and permanent record. I. The col- 

 lection of meteorological records from every part of the 

 world, from which to construct detailed tables showing the 

 relations of all the conditions named above, and may influ- 

 ence the growth and health of vegetation. 3. The construc- 

 tion of maps showing the geographical distribution of crops, 

 to be used in connection with the meteorological or climatic 

 data to be collected. 



PRELIMINARY ACCOUNT OF A SPECULATIVE 

 AND PRACTICAL SEARCH FOR A TRANS- 

 NEPTUNIAN PLANET. 

 By D. P. Todd, M. A., Assistant in the Office of the American 

 Ephemeris and Nautical Almanac. 



So early as the year 1834, Hansen was credited with ex- 

 pression of the opinion, in correspondence with the elder 

 Bouvard, that a single exterior planet would not account 

 for the differences between the tabular and observed longi- 

 tudes of the planet Uranus. Dr. Gould, however, in his 

 " Report on the History of the Discoveryof Neptune," says: 

 " I have the authority of that eminent astromener himself 

 (Hansen) for stating, that the assertion must have been found- 

 ed on some misapprehension, as he is confident of never 

 having expressed or entertained that belief." 



Professor Peirce's criticism of the investigations of Le 

 Verrier, to the effect that his predicted orbit of Neptune 

 was so widely discordant from its observed orbit as to in- 

 dicate that his computations did not pertain to the actual 

 disturbing planet, elicited from him the reply that the per- 

 turbations of Uranus due to a possible planet exterior to 

 Neptune might readily cause an uncertainty of 5" to 7" in 

 the fundamental data of his research. 



In 1866, the Smithsonian Institution published the gen- 

 eral tables of Neptune, by Professor Newcomb. In the in- 

 vestigation of its orbit the author proposed: "3. To inquire 

 whether those motions [of Neptune] indicate the action of 

 an extra-Neptunian planet, or throw any light on the ques- 

 tion of the existence of such a planet." He concludes 

 (page 73) that it is "almost vain to hope for the detection 

 of an extra-Neptunian planet from the motions of Neptune 

 before jhe close of the present century." 



In 1873, the Smithsonian Institution published the gen- 

 eral tables of Uranus, by Professor Newcomb. His suc- 

 cess in the treatment of the theory of Uranus was such that 

 astronomers generally may be said to have been satisfied 

 from the smallness of the longitude-residuals, that there 

 existed no evidence of perturbative action upon Uranus 

 other than that actually taken into account in the construc- 

 tion of the tables. It is well known, however, that since 

 the publication of these tables the error of longitude has 

 been increasing. 



Sometime in the spring of 1874, the first preliminary out- 

 line of the very simple method which I have here employed 

 in the treatment of planetary residuals with reference to ex- 

 terior perturbation, suggested itself to me. For more than 

 three years very little opportunity offered for consideration 

 of the problem of a trans-Neptunian planet. In August, 

 1877, however, I began to devote the larger portion of my 

 leisure time to the theoretic side of the question. It was 

 soon evident that no certain hold upon any possible cause 

 of exterior perturbation could be obtained from the resi- 

 duals of Newcomb's tables. And I may remark here that I 

 have consequently chosen the term speculative rather than 

 theoretic as applying more fitly to the investigation which 

 preceded the actual telescopic search. 



It did not seem to me that the magnificent researches of 

 Le Verrier and Adams on the perturbations of Uranus 

 should be taken as models in the present investigations, 

 for two reasons : 



(1) The residuals of longitude which must form the basis 

 of the investigation are not sufficiently well marked to jus- 

 tify the execution of so laborious a research, especially if 

 it be found that a simple, rational treatment, unencumbered 

 with the refinements of analysis, may be fairly interpreted 

 as indicating the position of an exterior perturbing body 

 with merely a rough approximation. 



(2) Even in the case of Uranus, and the theoretic search 

 for Neptune, where the residuals of longitude were very 

 strongly marked, many of the elements pertaining to 

 the disturbing planet, which Adams and Le Verrier sought 

 to determine theoretically, turned out afterward, when their 

 real values became known, to have been indicated with only- 

 meagre precision. Much less should we now expect these 

 elements to be given with any certainty in the case of a 

 planet exterior to Venus. 



This provisional treatment of the residuals of Uranus 

 was undertaken, then, as a preliminary to the proposed 



