Dec. II, 1873J 



NATURE 



105 



fluid covering the cilia ; but if tlie layer of fluid be very 

 thin, the cilia are readily destroyed. 



In conclusion, the authors stated that it would be pre- 

 mature, at this stage of the inquiry (which opened up 

 many points of interest in the physiology of respiration), 

 to generalise between physiological action and the phy- 

 sical and chemical properties of ozone ; but they pointed 

 out the fact that the density of ozone (O3 = 24) is slightly 

 greater than than that of carbonic acid (CO 2 = 22) ; and 

 that although the chemical activity of the substance is 

 much increased, yet, when inhaled into the lungs, it must 

 retard greatly the rate of diffusion of carbonic acid from 

 the blood, which accounts (from the accumulation of 

 CO2) for the venous character of that fluid after death. 

 From this point of view, destruction of life by ozone (with 

 the exception of its irritant action) resembles that caused 

 by an atmosphere surcharged with carbonic acid. This 

 has been found to be the case more especially as regards 

 the diminished number of respirations per minute, and 

 the appearance of the blood after death. If, however, 

 the analogy were perfect, the inhalation of an atmosphere 

 of ozonised oxygen would not have produced death, 

 because it is now well known, as shown by Regnault 

 and Reiset,* that animals can live in an atmosphere 

 containing a large per-centage of carbonic acid, provided 

 there is an excess of oxygen present. The amount of 

 oxygen in these experiments converted into ozone cer- 

 tainly never exceeded ten per cent. But the authors have 

 observed that an animal lives only a somewhat longer 

 time in ozonised oxygen than in ozonised air ; and they 

 are thus induced to regard ozone as having some specific 

 action on the blood that their future experiments may 

 elucidate. They are now prosecuting a series of researches 

 {a) on the action of smaller percentages of ozone ; (V) on 

 the action of ozone on noxious gases and effluvia ; and (c) 

 on any therapeutical or hygienic influences it may have 

 on the origin and treatment of zymotic diseases. 



THE ATMOSPHERIC TELEGRAPH \ 

 II. 



AVERY common question with visitors who witness 

 the departure of a train is, — If the boxes stick on 

 the road how do you manage to disengage them ? To 

 answer this question we shall notice in detail the various 



Fig. ^.— Diagram of the Chronograph. 

 2. Line ot the seconds' penduhmi. \ 



means employed in transmission, and thus we shall clas- 

 sify the derangements. 



Let us commence with the tubes. These may cause an 

 obstruction by a defect of the interior polish, by pro- 

 jecting joints, or by the escape of air through these jomts. 

 In the Paris system, however, precautions have been 



' " Air and Rain," by Dr. Angus Smith, p. i8i. (London, 1872.) 

 \ Continued from p. 66. 



taken against these three sorts of danger. The degree of 

 polish is sufficiently perfect, being obtained without ham- 

 mering, by pushing the tube along a mandril before it 

 becomes completely cooled. The joints represented in 

 Fig. 3 (p. 66), give an almost mathematical continuity to 

 the interior surface, and they are rendered air-tight by 

 means of India-rubber fittings. In this direction, then, 

 there is little risk of damage and the consequent stoppage 

 of the trains. In fact, since 1866 there has not been a 

 single accident caused by any defect in the tubes, and the 

 experiment is made upon a length of twenty kilometres 

 of pipes so constructed that joints occur every five 

 metres. 



The derangements arising from the machinery for com- 

 pressing the air are not of a special character, and need 

 not be particularised here. There remain the boxes. 

 Numerous types were tried before the system of the two 

 cases in tin and leather, which can be hermetically closed 

 and are easily opened ; from its simplicity this method 

 has been adopted. Nevertheless it does sometimes 

 happen that the boxes open during the journey ; how 

 this is caused is not easy to explain in each particular 

 case. Sometimes the collarette of the piston is in a bad 

 condition, and the air divides the train ; the cases are 

 separated, and the despatches are scattered in the tube. 

 At other times wrinkles are formed in the envelope of 

 leather, the effect of which is to wedge the train so firmly 

 that it is impossible to make it move. Another form of 

 derangement is when the piston breaks and the pieces are 

 lodged between the boxes and the tube. It is scarcely 

 possible to exhaust the series of accidents of this nature ; 

 the mean number of derangements in the working of the 

 system during the year is eight, and it is rare to find the 

 same cause occurring twice. When accidents do occur, 

 it is necessary to make all haste to relieve the train. 



Often alternate manoeuvres with compressed and rari- 

 fied air removes the obstruction ; at Berlin, for the same 

 purpose, M. Siemens employs water with which he forcibly 

 inundates the tube. The great thing is to extricate the 

 train without having to take the line to pieces. When 

 such means fail it is necessary to have recourse to the 

 operation of excavation ; and the necessity will be evi- 

 dent of a preliminary and sufficiently exact determination 

 of the place of derangement. The first means is indicated 

 by the method on which the system is worked. There is 

 at hand a reservoir of compressed air of a certain pres- 

 sure ; if this air is partly distributed in the section of the 

 tube comprised between the reservoir and the obstacle, 

 the new pressure is in a known r^itio to the original pres- 

 sure. In a word, Mariotte's k\v(', which regulates the 

 ratios of the pressures and volumes pf the same mass of 

 gas in two different circumstances, furnishes the means 

 of finding "//<• of the elements, volume, when we know 

 the three others, two pressures and one volume. 



M.Siemens prefers to measure the quantity of water 

 which it is necessary to distribute in order to flood the 

 line as far as the obstacle ; the accuracy ought to be very 

 great, but it must be acknowledged that the process, in 

 spite of its apparent .'implicity, has a somewhat primitive 

 aspect. It is not diflicuU to understand hQW this great 

 mass of water is introduced, but it is very difficult to con- 

 ceive that it can easily remove the obstacle. 



We may speak, finally, of an indirect means which is 

 illustrated in Fig. 4. The reader knows that when a 

 concussion is produced at the end of a tube filled with air, 

 this concussion is propagated in the air of the tube at a 

 speed of 330 metres per second. When the concussion 

 encounters an obstacle, it is reflected and returns to the 

 point of its origin at the same rate of 330 metres per 

 second. If then the time is noted which elapses between 

 the departure and the return, the period thus obtainedcor 

 responds to the passage of the concussion along a distance 

 equal to double the distance of the obstacle ; from an ob- 

 servation of the time, the distance can be easily calculat"-! 



