58o 



NATURE 



\April 2 I , I ; 



sometimes, as in the story of his early struggles while a 

 student at Upsala, and again at the period of his courtship 

 and his absence from the object of his affections, with the 

 air of the hero of a romance rather than the subject of sober 

 biography. It was to be expected that such periods in his 

 life-history would properly take forcible hold of the 

 sympathies of a lady biographer. It may be said at once 

 that the author has carefully consulted the proper authorities 

 — Stoever, Piilteney, Smith, Jacl<3on, &c., and duly acknow- 

 ledged her indebtedness to them ; and occasionally, with 

 more jubilation than mere complacency, her disregard for 

 them when they fail by disagreement among themselves, 

 or otherwise, to satisfy her. One can hardly say fairer 

 than that The first impression of the book is unfavour- 

 able ; in fact, it is felt that one cannot take it seriously. 

 That it is not meant to be so taken altogether is manifest 

 from such statements as that "by Hok rather than by 

 Krok Carl's name was enrolled," &c. Apart from this 

 kind of thing, however, there is often a temptation to 

 smile at the wrong places. The author's observations on 

 men and things in general are frequent and fearless. For 

 e.\ample, in discussing an architectural matter she wonders 

 at " the usually perceptive Fergusson '' not recognising 

 the significance of a feature well known to ordinary 

 writers on Swedish architecture. Doubtless Mr. Fergus- 

 son would have valued this gentle way of describing him, 

 so unlike the manner of those " cock-a-hoop and over- 

 bearing young scientific men " whom the author prophesies 

 will be " charming at forty." There is a superabundance 

 too of quotations in the book beyond the legitimate 

 quotations from Linnsus himself and writers of his life. 

 Indeed, to put it in the fashion of that biographer of 

 Linna'us whom she calls "dear old Stoever," she can rarely 

 keep her course clear of the Scylla of her own wisdom and 

 the Charybdis of miscellaneous quotations from Carlyle 

 and a great variety of other writers. 



The ancestors of Linnaeus, his life from boyhood and 

 school-days, throughout his University career, are discussed 

 with picturesque descriptions of the land and the people. 

 ■We then come to his debut in the treatise on the sexes 

 of plants, in answer to Wahlin's " Nuptise Arborum 

 Dissertatio." "This," we are told, " was a blooming new 

 idea in the summer of 1730." He is then followed through- 

 out his travels in Lapland, Dalecarlia, his fruitful visits to 

 Holland, England, and France, his return to Sweden and 

 career at home, including his subsequent journeys — to the 

 end. The following passage will give a fair illustration 

 of the style of the more extravagant passages in the 

 book: — 



" Linnaeus broke down : he dropped like the begonia at 

 the last — the flower that had always interested him so 

 much, with its male and female flowers so graceful and 

 so differing. The common begonia, that most interesting 

 and elegant of plants, is jointed all the way up, and as it 

 withers the joints become separated and in shape like the 

 bones of the human limbs ; they drop apart, and fall like 

 dry bones upon the ground. This family is a botanical 

 study in itself ' Many begonias are remarkable for the 

 production of adventitious buds,' " &c. 



In spite of this amazing style it must be owned that 

 apart from such small matters as spelling Linnean, in the 

 name of the Society, " Linnsan," the book is wonderfully 

 correct in the main features of the life of Linna:us, and 

 once the reader is accustomed to absurdities such as we 

 have noted, it becomes a readable narrative. The worst 

 of it is that one is hurried off to somewhere between China 

 and Peru for an illustration of some sober fact, and 

 this without sufficient warning to the unwary reader. 



Sur line nouvelle M^thode de faire des Mesures absohies 



de la Chaleur ravonnante. Par Knut Angstrom. 



(Upsal: Berling, 1886.) s 



In this quarto pamphlet of seventeen pages (with a plate) 



the author claims to give a simple method for determin- 



ing the absolute measure of radiant heat, and describes a 

 self-registering apparatus which gives the intensity of 

 solar radiation at any instant, as also the total heat 

 received by the absorbing surface in a given time. 

 Two circular copper disks are alternately exposed to the 

 source of heat and screened from it, and a thermo-electric 

 couple and galvanometer give the differences of their 

 temperature. The method consists in finding accurately 

 the average time for the tciiiperature-diffi:rencc of the two 

 plates to be a given (small) amount, positive and negative 

 in turns. By the aid of Newton's law of cooling, which 

 is applicable in this case, the author proves that the 

 intensity of the radiation is proportional to the tempera- 

 ture-difference directly, and the time inversely, and that 

 it is quite independent of the constant of cooling. To 

 verify the last conclusion, the author measured with an 

 instrument of this kind the radiation of a constant source 

 of heat under varying conditions of cooling, and he found 

 that the influence of cooling was completely eliminated. 



In the construction of the self-registering actinometer 

 founded on this principle, the absorbing surfaces are 

 those of a differential thermometer, and the temperature- 

 differences are marked by the movement of a thread of 

 mercury in the communicating glass tube. When the 

 thread has moved a certain distance, corresponding to a 

 known temperature-difference in the two bulbs, an electric 

 circuit is completed, and an electro-magnet turns the 

 instrument through 180', thus reversing the positions of 

 the screened and unscreened bulbs. By the usual clock- 

 driven pencil and revolving cylinder, a curve is drawn of 

 which the abscissa is proportional to the time, and the 

 ordinate to the number of turns which the instrument has 

 made in the time. It is then shown that at any instant 

 the intensity of the radiation is proportional to the 

 tangent of the angle which the curve makes with the axis 

 of abscissae, and that the total heat received in a given 

 time is proportional to the difference of the ordinates cor- 

 responding to the beginning and end of the time. The 

 constants by which these variables are to be multiplied 

 must be found by comparison with an absolute instrument 

 like that already mentioned, and the necessity for this 

 comparison may prove an obstacle to the general use of 

 the instrument. Notwithstanding this drawback, the 

 author claims for his invention that it gives results in 

 accordance with those of the absolute instrument, and 

 that it works as satisfactorily on stormy days as on calm 

 ones.. There is no doubt that the instrument is deserving 

 of a fair trial, and a comparison of the results obtained 

 from it and from some other recent forms of actinometer, 

 would be of great value. 



The paper is carefully written and printed, and we have 

 noticed only two unimportant slips : one on p. 9, last line 

 but one, where 40'o should be 41 o ; and another on p. 16, 

 line 9, where plus should be mains. T. H. C. 



LETTERS TO THE EDITOR 



[The Editor does not hold himself yesnonsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake to 

 return, or to correspond with the iv -'ters of, rejected manu- 

 scripts. No notice is taken of anouvmous communications. 



[The Editor urgently requests correspon »' I's to keep their letters 

 as short as possible. The pressur, ■■/ kis space is so great 

 that it is impossible otherwise to in • .- he appearance even 

 of communications containing inti ing and novel facts. ] 



■Vitality and its Definition 

 While warmly congratulating Prol Judd upon the ability 

 with which he has brought "out into I'-ar relief the analogies 

 between the science dealing with the m il kingdom and those 

 concerned with the animal and vegeta kingdoms," I cannot 

 but think he has a little understated le difference between 

 organic and inorganic matter. As this 1 is arisen from a mis- 

 eonception of Mr. Spencer's definition 'ife — a misconception 



