142 



KNOWLEDGE. 



[JrxE 1, 1898. 



The table further shows the area and the number of 

 plots under experiment in each case ; and it may be stated 

 that the total area under exact and continuous experiment 

 has been for some years, and is at the present time, about 

 forty acres. 



To cultivate and simultaneously investigate scientifically 

 the products of such an extensive series of plots of ground, 

 a staff of workers of no mean order is of course necessary. 

 A number of general assistants, therefore, are engaged to 

 superintend the field experiments— that is, the making of 

 the manures, the measurement of the plots, the application 

 of the manures, and the harvesting of the crops ; also the 

 taking of samples, the preparation of them for analysis or 

 preservation, the determination of dry matter, ash, etc., 

 and the keeping of the meteorological records. There is a 

 permanent laboratory stafl' of two, and sometimes three, 

 chemists, and three or four computers and record-keepers 

 for calculating and tabulating field, feeding, and laboratory 

 results, copying, etc. In addition to a large staff of this 

 kmd, the best professional assistance has been called in 

 from time to time. Among these may be mentioned Prof. 

 Frankland, who determined the nitrogen as ammonia, as 

 nitric acid, and as organic nitrogen in many samples both 

 of the rain and of the various drainage waters collected at 

 Rothamsted; Prof. \V. J. Russell estimated the sulphuric 

 acid in some of the monthly mixed samples of rain water ; 

 the late Dr. Voelcker determined the nitrogen, and likewise 

 the incombustible constituents, in sixty-five samples of the 

 drainage waters ; Dr. Richter has made more than eight 

 hundred analyses of the ashes of various products, animal 

 and vegetable, of known history ; and the late Dr. Pugh 

 took a prominent part in the experiments to determine 

 whether plants assimilate free nitrogen, and also various 

 collateral points. 



Samples of all the experimental crops are taken and 

 brought to the laboratory. Weighed portions of each are 

 partially dried, and preserved for future reference or 

 analysis. Duplicate weighed portions of each are dried at 

 100° C, the dry matter is determined, and it is then burnt 

 to ash on platinum sheets in cast-iron mufHes. The 

 quantities of ash are determined and recorded, and the 

 ashes themselves are preserved for reference or analysis. 

 In a large proportion of the samples the nitrogen is deter- 

 mined ; and in some the amount existing as (dbumimids, 

 iimidfs, and nitric acid. There is now a collection of more 

 than forty-five thousand bottles of samples of experimen- 

 tally grown vegetable produce, of animal products, of ashes, 

 or of soils, besides some thousands of samples not in 

 bottles ; and the laboratory having become very incon- 

 veniently full, a new detached building — a " sample house " 

 — was erected in the autumn of 1888, comprising two 

 large rooms for the storing of specimens and for some 

 processes of preparation, and also a drying room. 

 The general scope and plan of the field experiments 

 has been to grow some of the most important crops of 

 rotation, each separately, year after year for many years 

 in succession on the same land, without manure, with 

 farmyard manure, and with a great variety of chemi- 

 cal manures ; the same description of manure being, 

 as a rule, applied year after year on the same plot. 

 Experiments on an actual course of rotation without 

 manure, as well as with different manures, have also been 

 made. 



Having thus indicated the scope of the researches at 

 Rothamsted, the resources available, and the disposition 

 of the estate, we shall endeavour in a subsequent article 

 to present some of the remarkable results which have been 

 derived therefrom, and the bearing of the conclusions 

 arrived at on practical agriculture. 



NOTES ON COMETS AND METEORS. 



By W. F. Denning, f.r.a.s. 



Lewis Swift. — The famous American astronomer, Lewis 

 Swift, well known for his discoveries of nebulae and 

 comets, furnishes a remarkable example of the retention 

 of brilliant observational capacity to an advanced age. 

 Though the time of his birth dates back to 1820, Feb- 

 ruary 29th, he still discovers numbers of exceedingly faint 

 nebuhr, and occasionally announces a new comet. The 

 most recent of his cometary discoveries was in 1896, April, 

 when he was in the seventy-seventh yi'ar of his age ! His 

 success has certainly been astonishing. No other comet- 

 finder appears to have effected discoveries at a period so 

 late in life as the veteran of whom we are speaking. Pons 

 was about sixty-six years old, Mechain fifty-five, and 

 Messier sixty-eight, when they sighted their last comets. 

 Let us hope that Swift will yet be spared some years to 

 add to his laurels by the discovery of further objects in 

 the fields where he has already laboured so long and with 

 so much distinction. 



Feriine'ti Comet (Marfh 19th). — This object is still 

 visible, though becoming very faint. At the early part of 

 June its brightness will be only one-fifth that at discovery. 

 \n ephemeris was given in the last number of Knowledge. 



Periodical ( omets. — The comets of Wolf, Encke, and 

 Tempel (1867, II.), are shortly expected to appear, but 

 the circumstances are not favourable. Pons-Winnecke's 

 comet is now exceedingly faint. The following are ephe- 

 merides : — 



Comet Wolf. 



June 1 



Comet Tempel (1867, II.). 

 11 41 11 +13 501 



177 



Comet Wolf is approaching the earth, but it will not 

 come as near as in 1891, and will probably remain a faint 

 object during the whole of this apparition. It will reach 

 its perihelion on July 4th, though it will continue to 

 become very gradually brighter until the close of October. 

 Comet Encke is rapidly advancing nearer to the earth 

 and its apparent brightness increasing, but its position 

 is not favourable for northern observers, as its motion 

 carries it very quickly southwards. During the month 

 the comet passes from the north-west extremity of Gemini 

 to the south-east border of Monoceros. Tempel's comet 



