6o8 



NA TURE 



[April 26, 1906 



Here again was an increase, and one which legume 

 tubercles could not be brought in to explain. It was only 

 when Lawes and Gilbert, trying to get chemical evidence, 

 grew feeble, unnatural plants under unnatural conditions 

 that they failed to get a similar increase of nitrogen. On 

 this ground alone they supported the theory of the in- 

 ability of the plant to draw nitrogen from air, and thus 

 supported themselves in the notorious controversy with 

 Liebig, the distinguished German who has done more for 

 agriculture than any other man of science, and who, bv 

 the way, denounced the Rothamsted experiments in no 

 measured terms (see the " Natural Laws of Husbandrv," 

 pp. 157 and 298). 



Obviously, therefore, to show that plants fix free 

 nitrogen is to undermine the work with which Rothamsted 

 is chiefly identified. 



Your readers will understand the value of the critique 

 when they know that the initials under it are those of 

 the director at Rothamsted. Thos. Jamieson. 



Glasterberry, Milllimber, April 10. 



I AM glad to see that Mr. Jamieson does recognise the 

 necessity of some proof of his assertion that nitrogen has 

 been fixed by the plants he has been examining ; he now 

 says that "it may now be forthcoming." When Mr. 

 Jamieson 's " may " has been converted into " is," chemists 

 and botanists may begin to consider his speculations as to 

 how the process is effected. For let us bear clearrj in 

 mind that Mr. Jamieson 's theories onlv deal with the 

 question of how the nitrogen is fixed ; that it is fixed at 

 all he takes for granted. 



But what an unlucky series of experiments to enforce 

 his argument has Mr. Jamieson selected from Rothamsted. 

 He quotes three non-leguminous crops, wheat, barley, and 

 roots, which when grown continuously on the same' land 

 for a period of twenty-four to thirtv 'years have removed 

 on the average 16 lb. to 22 lb. of "nitrogen per acre per 

 annum. Rut at the beginning of the experiments the soil 

 was estimated to contain about 3000 lb. per acre of com- 

 bined nitrogen, i.e. five times as much as the thim years' 

 cropping has removed. Furthermore, analyses have' been 

 made and published which show that the soil has lost 

 nitrogen during this period ; the average loss on the 

 unmanured wheat plot from 186=; to i8q 3 was 10 lb per 

 acre, which if added to the 5 lb. per acre of combined 

 nitrogen brought down bv the rain pretty well accounts 

 or the iq lb- per acre removed in the crop. Knowing as 

 ^reat reserves of nitrogen in the 



ce do that there ar 



soil, and that they slowly become available for the plant 

 trier- ,s no reason to suspect that these non-leguminous 

 plants have needed 10 take anv nitrogen from the air t.. 

 yield the crops that are recorded. 



Then Mr. Jamieson quotes the output of nitrogen from 

 two leguminous crops, clover and beans, and it is iust 

 about double that of the non-leguminous crops ; very much 

 more than double, in fact, if calculated on the number of 

 crops actually obtained, and not spread over an average of 

 years. Yet Mr. Jamieson goes on to say that the " legume 

 tubercles cannot be brought in to explain this; when 

 the only crops yielding anything like an average amount 

 of nitrogen are the iw... beans and clover \vhich by- 

 accepted theories obtain nitrogen from the air bv mean's 

 ot the bacteria in the " tubercles " on their roots. Most 

 people regard these experiments as a very sound piece of 

 evidence for the fixation of nitrogen by leguminous crops 



Let us consider these results from another point of view 

 the wheat crop without nitrogen, but with phosphoric acid 

 and potash, at Rothamsted averages about fifteen bushels 

 per acre, barley about twenty bushels per acre, the root- 

 crops (mangels) about 5.4 tons per acre : this is the sort 

 ot level that is reached when the crop has to rely upon 

 the air and the original stock of nitrogen in the soil. Is 

 Mr. Jamieson proposing to recommend farmers to grow 

 crops nf this size, for that is what they must come to when 

 they have only the air to draw upon 'for their nitrogenous 

 food ? 



In his concluding paragraph Mr. Jamieson appears to 

 suggest that Lawes and Gilbert ran the Rothamsted ex- 

 NO. 1904, VOL. 7$} 



periments as a sort of conspiracy to disguise the truth in 

 favour of a prepossession of their own, and that after their 

 death the body of scientific men who constitute the com- 

 mittee of management engaged their present director to 

 continue the traditional fraud ; this is a " theory " which, 

 like others of Mr. Jamieson 's, must require a robust con- 

 fidence in the credulity of his disciples. A. D. H. 



A Horizontal Rainbow. 



I shall be much obliged if a reader of Nature will 

 kindly give me an explanation of the following : — 



I was on Loch Lomond yesterday, a perfectly still, 

 cloudless day, with haze as from east wind over the moun- 

 tains. There had been hoar-frost in the morning. About 

 10.15, from the deck on the steamer at Balloch, I observed 

 a broad patch of strong prismatic colours on the abso- 

 lute l\ calm surface of the loch about half a mile from tin 

 pier, my back being turned to the sun. I watched this 

 patch with interest, and, as the steamer approached it, 

 it gradually lessened and almost disappeared ; but in its 

 place a rainbow, faint but distinct, lay horizontally on the 

 surface of the water, one end resting beside the bow of 

 the steamer and the arc curving for perhaps 150 yards 

 ahead, the sun still being behind me. I never saw any- 

 thing of this kind before, and was much interested. The 

 loch was absolutely calm, reflections of sea-gulls, &c, 

 being perfect. 



The only explanation I can think of is that, after the 

 hoar-frost and possible sea-fog of the earlier morning, there 

 was just a film of fog left undisturbed on the calm surface 

 of the water, sufficient to break up the rays of the sun 

 into their component parts. W. R. M. Church. 



Western Club, Glasgow, April 12. 



THE SAN FRANCISCO EARTHOVAKE OF 

 APRIL 18. 



IN the immediate presence of a great catastrophe, 

 in which hundreds of lives have been lost, and 

 San Francisco, the "Queen of the Pacific," has been 

 almost entirely destroyed, it is not to be expected thai 

 details of much scientific value should be recorded. 

 All that is here possible is to describe briefly the 

 course of events, to trace in rough outline their con- 

 nection with former shocks and with the geological 

 history of the district, and to refer to the unfelt earth- 

 waves registered at distant observatories. 



Nature and Effects of the Earthquake. 



Though the coast of California from San Francisco 

 to Los Angeles is one of the chief seismic regions of 

 the globe, the first and greatest shock was heralded 

 by no warning tremors or earth-sounds. It occurred 

 at 5.13 a.m. (that is, 1.13 p.m. Greenwich mean time), 

 perhaps, as the seismographic evidence would imply, 

 a lew minutes earlier. As in all tectonic earthquakes 

 of the first magnitude, the duration of the shock was 

 considerable, not less than two or three minutes, and 

 it was in this time that the chief part of the destruc- 

 tion, so far as it was directly due to the earthquake, 

 was accomplished. Five minutes later another and 

 less violent shock was felt, and, in the midst of almost 

 continuous tremors, a third prominent shock took 

 place at 8.15 a.m., and others shortly before 10 a.m., 

 and about 1.30 and 7 p.m. None of these seems to 

 have been registered in European observatories, but 

 they sufficed to throw down walls already damaged. 

 Soon after the first shock fires broke out in several 

 parts of the city, and spread rapidly, the water-mains 

 having been injured. Attempts, on the whole su,( - 

 cessful, were made to limit their extension by blow ing 

 up passages through the crowded parts, with the 

 result that about one-quarter of the city may be ulti- 

 mately saved. 



Like Charleston, .which was so seriously damaged 

 by an earthquake twenty years ago, San Francis. ;o is 



