Mar. 23, 1888.] 



SCIENTIFIC NEWS. 



279 



usefulness, to take advantage of the classes. When will 

 the Lord Mayor of London bring himself into sympa- 

 thetic touch with the great neglected masses of London, 

 and issue such an invitation ? When we visited 

 Brussels, we made a tour of free night schools accom- 

 panied by the Mayor, the Head of the Educational De- 

 partment, and the Deputy Speaker of the House of 

 Representatives. Whoever heard of Ministers of State 

 and the Lord Mayor of London accompanying a foreign 

 Commission on a tour of free night schools in this great 

 city ? I suppose there are many good reasons why such 

 a thing should not happen in the wealthiest and most 

 populous city in the world, but I need only name one. 

 they would not find the schools — at least of the character 

 of the splendid free drawing schools of Brussels,"because 

 they do not exist in London, nor in any city or town 

 in the United Kingdom. 



Living Lights; a Popular Account of Phosphorescent 



Animals and Vegetables. By C. F. Holder. London : 



Sampson Low, Marston, Searle and Rivington. 



A monograph of phosphorescence has long been 



' wanted. It is a heavy burden if we wish to ascertain 



precisely all that is known concerning this interesting 



phenomena to search through the scores of works, 



memoirs, and dissertations in which the facts are buried. 



Hence we opened Mr. Holder's book in the anticipation 



of pleasure and profit. 



These hopes have only been partially fulfilled. The 

 author gives us a number of very interesting cases of 

 phosphorescence, but he makes little attempt to explain 

 what these instances teach. Save to a small extent in 

 the preface, he does not enter upon the consideration of 

 phosphorescence in general, and of its several modifica- 

 tions. That very decided modifications do exist may be 

 regarded as certain. Some of the phenomena here 

 described cannot rightly come under the heads of " living 

 lights," since no life is concerned. The first step in the 

 study of this very difficult and complicated subject should 

 be to sort out from each other the different classes of 

 phenomena here included. The luminous showers, 

 hail-stones, snow-flakes, the light emitted on striking or 

 grinding fluor spar, felspar, sugar, etc., cannot be explained 

 on the principles applicable to luminous animals and 

 plants, whether living or decaying. Leaving such 

 phenomena on one side we find that Radziszewski has 

 divided all phosphorescent bodies whose luminosity 

 admitted of being tested into two classes : — i. Such as on 

 the addition of an alkali become luminous, when they 

 already contain active oxygen, which is formed in them 

 under the influence of an exciting agent, such as, e.g., 

 the light of the sun. 2. Such as on the addition of 

 alkalies form active oxygen and phosphoresce during 

 their combination therewith. The results of Radziszewski 

 seem, indeed, to show that active oxygen is the main 

 agent. But there are difficulties in abundance. The 

 emission of the light seems in some cases to be regularly 

 intermittent, like the lamps of a revolving beacon, and 

 in others to be suppressed at the will of the animal. Of 

 this latter phenomenon Mr. Holder gives an instance in 

 the breast of a heron {Myctiardca grised) and of a blue 

 crane (Ardea coerulea). But as the bird was observed at 

 the distance of 150 feet, it is possible that it may, as he 



suggests, have occasionally altered its position, which 

 would account for the temporary disappearance of the 

 light. He mentions that the bird after being shot 

 " died slowly, the light gradually dying out and disappear- 

 ing entirely with death." 



There are, however, cases where dead organic matter 

 retains its luminosity, as it is recorded in this work. 



We may mention that the breast of a heron seems to 

 have a strange fascination for fishes, in daylight as well 

 as in the dark. 



Mr. Holder quotes the statement of Dr. Dubois that 

 the light of the fire-fly {Pyrophorus) has an exceedingly 

 beautiful spectrum, " continuous, without dark or 

 brilliant rays ; and that appears most remarkable, the 

 composition of the light was found to change with its 

 intensity." Mr. W. G. Levison, of Brooklyn, has 

 examined the light of the fire-fly (species not stated) and 

 gives a rather different account. He finds that the blue 

 and the violet rays are absent and that the less refran- 

 gible raj's predominate. It is very probable, however, 

 that the light of different species is not identical. A 

 spectroscopic examination of the lights, as far as practic- 

 able, of all phosphorescent substances is urgently needed. 



On the vexed question of the lantern-flies {Fidgara 

 lanternaria) of South America, and F. candelaria of China 

 Mr. Holder suspends judgment. Modern scientific 

 opinion, certainly, is against the luminosity of this fine 

 insect, but it is difficult to set aside the positive assertion 

 of Madame Merian, who in many cases has been found 

 to be an accurate and trustworthy observer. 



The uses of phosphorescence are the subject of an 

 interesting chapter and must be left to the decision of 

 future observers. 



The author states in his preface that his work is mainly 

 addressed to young scientists, to their unscientific elders, 

 and to the boys and girls who have not yet been led to 

 feel an interest in Nature's works. We believe that it 

 is well adapted to lead such persons on to become 

 observers, and hence, as a whole, it is fairly entitled to 

 whatever commendation we can bestow. The plates are 

 not only beautiful but appropriate. 



The Rothamsted Experiments on the Growth of Wheat, 

 Barley, and the Mixed Herbage of Grass Land. By 

 William Fream, B.Sc, F.L.S., etc., etc.. Professor of 

 Natural Historj' in the College of Agriculture, 

 Downton, Salisburj'. Published b}' Horace Cox, 

 r/i« F/rfrf Office, Strand, London, W.C. 1888. 8vo, 

 235 pages. 

 This book is founded on facts accumulated during 

 more than forty years of accurate scientific experimenta- 

 tion, is nearly unique, and must almost necessarilj' be 

 of great value. It contains the results of the far-famed 

 researches in agriculture which have been, and are still 

 being conducted by the eminent investigators. Sir J. B. 

 Lawes and Dr. J. H. Gilbert. The very numerous 

 reports of these gentlemen are spread far and wide in a 

 multitude of publications, and although extremely valu- 

 able, they are as a whole practically inaccessible ; more- 

 over, a good many of them are out of print, and from 

 these circumstances they would in a few years be lost to 

 the public. 



Fortunately, in Professor Fream there has been found 

 a faithful and competent interpreter of these valuable 

 memoirs, and in the present volume he sets before his 

 readers a terse and clear account, not onl}' of the 

 Rothamsted experiments on the growth of wheat, barley. 



