October, 1905.] 



KNOWLEDGE & SCIENTIFIC NEWS. 



251 



some of them possess a sliofht permanent radio-activity 

 of tlieir own. This is the case of any freshly-gathered 

 plants and their parts, such as ffrass, fruit, fioAvers, and 

 leaves, while the same plants, after beintf dried, show, 

 at most, some slight traces of temporary radio-activity. 

 In order tO' ascertain whether animals also have 

 such a permanent radio-activity of their own, Tom- 

 masina constructed a muff-shaped cag;e of wire g-rating, 

 forming- two' concentrical cylinders between which an 

 annular space of some centimetres was left free 

 (Fig-, i). The two cylindiica! wire gyrates were closed 

 both at the top and below by metal discs perforated in 

 the centre to allow of the caape being- slipped readily 

 ()\er the insulated metal cylinder of the Elster and 

 Gcitel apparatus, serving to measure the radio-activity. 

 On the blackened cylinder of this electroscopic outfit 

 takes place the dispersion of electricity due tO' the 

 radiation from the animals put in the cag-c ; as the 

 latter has the shape of a narrow circular corridor, the 



CORRESPONDENCE. 



Pig- 3- 



animal is allowed to> move freely while remaining 

 always at practically the same distance from the elec- 

 trified dispersing cylinder (see Fig'. 3). The cage con- 

 taining the animal experimented on is next placed in 

 the interior of the great cylindrical metal cylinder seen 

 on the left of Fig. 2 ; this is blackened both within and 

 without, so as to eliminate any dispersive action of 

 ultra-violet rays. 



Though these highly interesting experiments on the 

 radio-activity of birds had tO' be discontinued tem- 

 porarily. Dr. Tommasina was able tO' state that the 

 phenomenon is quite general in character. The most 

 interesting result is, however, that the intensity of the 

 radio-active radiation is stronger with grown indi- 

 viduals than in young ones, and depends also^ on the 

 state of activity or rest of the subject. In fact, radio- 

 activity seems to he -proportional to muscular activity or 

 vital energy. 



This phenomenon, that could be called bioradw- 

 activity, has doubtless a rather intimate relation with 

 life, and from this point of view its further investiga- 

 tion will probably give results of a great bearing both 

 on philosophical and practical problems. 



The Equa-tiorv of Time iheory. 



To THE EurroRs of " Knowludgk & Illustkatkd 

 Scientific News." 

 Sirs, — In your number for August, a question is put to 

 me by your reviewer in his observation upon the first part 

 of my woiU, " Some Elements of the Universe Hitherto Unex- 

 plained." I am sure you will permit me to reply, the more 

 especially as the question of your reviewer raises an interest- 

 ing issue upon the subject. The question has relation to 

 Chapter IV., which asserts that the existing theories do not 

 account for the cause of the sun's irregularity in time, and fur- 

 nishing a new explanation. The question of your reviewer is 

 — " How would he deal with an obliquity of 90° ? " — meaning, 

 I suppose, if the obliquity of the ecliptic were go°, instead of 

 as at present 23° 27' 5"'g2. To answer this it is necessary to 

 use the reputed effect of the present obliquity as the basis for 

 gauging the effect at yo°. To limit my reply as much as 

 possible, I will confine my remarks to the 30° immediately fol- 

 lowing the March equinox. The advantage of taking these 30^ 

 is that the theoretical causes of the sun's irregularity are here 

 all acting in the same direction, if they act at all ; and the sun 

 is at its average distance, the actual mean occurring on 

 April I. If a celestial globe be referred to, it will be seen that 

 the distance along the ecliptic from the equinox to meridian 30 

 is just over ^2 degrees of arc, or 2° more than along the 

 equator. If the obliquity were increased to an angle of 45', it 

 will be found that S° is added before the 30th meridian is 

 reached. At an angle of 70° the e.xtra distance is 27°; at 80'^ 

 it is 41°; at 85° it is 50°; and at go°, to make up the full 

 arc of go°, it is evident that 60° is required. Traced in 

 this way, it is seen that if the present obliquity has an effect, 

 the increase would continue up to go° ; it would then decrease 

 in the same ratio. What then would be the result of moving 

 the ecliptic the extreme limit of go° from the equator, or at 

 right angles to the equator ? At the equinoxes the axis of the 

 earth would be parallel to the equator. Still there would be 

 12 hours day and 12 hours night, just as now. But at the 

 December solstice the south pole of the earth would point to 

 the sun, and at the June solstice, the north pole on June 21, 

 the sun would be almost stationary in the mid-heavens. But it 

 would begin a small spiral, and by noon next day would cross 

 the iSoth meridian about one degree from the north pole. 

 The following day it would apparently describe a slightly 

 larger spiral, and continue to increase the spiral day by day, 

 and also to cross the iSoth meridian with an advance at the 

 same rate that it now moves along the ecliptic. As the 

 obliquity of go° results in this small circle in the sky 

 at the solstice (during which the sun will pass over less 

 than 6° of arc), will it occupy a less period of time 

 than the circle twice the size next day, or any of the 

 increased circles up to the time of the sun reaching the 

 equator and passing round the whole 360^ — or more than 60 

 times the arc distance of the small circle. It is evident 

 that all will occupy the same time, because the sun does not 

 move, but the appearance of its movement is due to the revo- 

 lution of the earth, and no variation can be detected in that. 

 It is thus seen what a valuable argument the question of your 

 reviewer supplies against the existing theories, because the 

 placing of the ecliptic at right angles to the equator not only 

 shows that at the greatest possible angle no difference is made 

 in the causes said to produce the sun's irregularity; but by 

 removing the effect of the earth's revolution in its orbit from 

 the effect of its revolution on its a.xis, it is made plain that 

 although the sun would appear to move from the south pole 

 to the north pole in the course of six months (or nearly nine 

 times its present change of altitude), yet it would not entail 

 any difference in time because it must be performed in the 

 period of the earth's revolution on its axis. The irregularity 

 in the sun's motion, due to causes which I explain in my work, 

 would not be ah'ected by the change of obliquity, and would be 

 indicated by a variation in its latitude. If the Ca;3ar of obli- 

 quity be appealed to, let the decision be according to what is 

 claimed. In the period the sun ought to move from the 

 equinox to meridian 30 ; if its motion be measured along the 

 line of the ecliptic, it must be more than 2° behind time. Two 

 degrees means nearly two days, or 1 hour 36 minutes per day. 



