Our Paris Letter.

Thames Star, Volume VII, Issue 2016, 21 June 1875, Page 3

Our Paris Letter.

(fbosi our own correspondent.) ,/'■■ ' Paris; April 17, 1875. ATMOSPHERIC INFLUENCES. Professor Bert has ably studied the effects of barometrical pi'essure on animal life, and M. Jourdanet, who has for a long. (time lived and exercised the profession of medicine in high altitudes, has exhaustively treated the question of the influence of the atmosphere on human existence. He has observed, rather than experimented ; and judges from the point of view, Jthat the true.nature of ; external influences can be better ascertained by the maladies they cause man, rather than the health they procure him. Balloons, . tip to the present, hare been the chief and "v best sources for testing that unsettled question—the diminution of heat in proportion to altitude.; M. Jour danefe draws attention to the plateau of whicK Mexico is the chief city; there the air is fresh, the sky pure, the light-resplendent, and the district is 2190 yards above the level of the sea. The mean temperature at Mexico is 63 degrees,;while at Vera. Cruz ibis- 79 ; thus /indicating; a; diminishing temperature of one degree per 137 yards. But this ratio of diminution is not subject to the same law when one ascends in a balloon. In the Himalayan Chain, the mountain masses rise so gradually, that heat;is maintained at extremely high altitudes, antl ? Simla is the ; important health station Of India. The amount of watery vapor in the air exercises an important influence;on the phenomena of life. Mexico city is surrounded by lagunes, yet its atmosphere is dry and the soil arid ;".thirfdryness of the- air allows the rays of the pun to arrive more freely, so that the soil becomes warmer than the air, and the branches of the trees warmer than their roots. The plateau of Thibet, and the elevated plains of Turkestan prove iihat masses of mountains can supplement the solar rays in modifying the rudeness of the atmosphere. The regions of South America, Abyssinia^ 'and parts of the Alps, have populations struggling with a rarefied atmosphere; • and consequently a diminished supply of oxygen.. M. Jourdanet asserts that in Mexico, as well as in all. the .old Spanish colonies, the Indian and white races are

dying out, while the mixed race alone increases. Strange,! the inhabitants of th c elevated districts of South America do not. display, the stimulating and vivifying effect' of temperate ' zones ; the people are calm and listless, pale or yellow, rather., than.,rosy and fresh, and the absence of vigor is general. On examining the blood of some .of his patients, Jourdanet did not discover any diminution of oxygen in the blood, but when the atmospheric, pressure .was diminished/by bnefourtK the oxygen in the arterial blood became less. -This natural, fact corroborates thel direct experiments of M. Bert. 3}he. reduction in the normal--supply, of 'oxygen in the system after reaching a certain altitude, produces what is. familiarly known as " mountain sickness; " «sex-,p_e,rie.riced-;by L the followers of Cortez> by Humboldt, and De Saussure &c, and

which yery much resembles sea-sickness.; Thei; increased number of respirations - does not > appear .:to> compensate, for this deficiency of oxygen, and the danger iforVlife "at: high;altitudes arises from the difficulty of becoming warm, which Augments inproportion to vthe necessity _ .ifor jheat. Only, the Timorous and trained tor^Sdpi^'tSttbsif '"'?" " i v ;

, , CHANGE OF SEASON. • Spring frosts are not only very trying for agriculture, but ior the public health, »nd they differ not only in intensity, but in origin. Dew, that the ancients re- ' gaided as a exudation of the stars, etc., is • the result of the nocturnal radiation of ' the soil. The strata of air next the soil . becomes warm during the day, the humidity produced by evaporation saturating them 5 night arrived, and the sky ' unclouded, the rapid radiation of the•arth's heat cools ,the strata of air, and condenses the vapor in the form of dew; juit aa a piece of cold glass carriod .into a warm and humid room becomes covered with vapor. It is thus that autumn and spring are the seasons for dew, because short cays of heat are followed by long nights of cold. In winter this vapor is rare or absent on account of the cold, and in summer the soil is too warm to ' condenie it. Dew and white frost have about the same relationship, as rain and snow ; the greater cooling of the soil at night to below zero, and the temperature of the lower strata of tKe air descending nearly to the freezing point, the' vapor falls in the form of microscopic drops, forming beautiful crystals. ' Below zero there is no watery j vapor in the air to become precipitated, j •' consequently,' there can be no white frost. ( Often where the atmosphere is heated for - a few hours by the sun in cold weather, , the strata of air next the soil parts with its acquired vapbr^as white frost, and when, during along frost, warm winds suddenly bring much watery vapor, the latter is condensed as verglas or glazed frost. If this vapor be not abundant, it forms hanging crystals, of a fairy-like aspect on walls, branches of tree &q. But there is another kind of spring frost, which is very disastrous, and arrives when least expected. According to IJepker, it is caused by the excessive activity of equa- • torial currents, out of proportion with the season and the sun's altitude, thus producing a mild winter, but later attracting a kind of "gulf stream" of cold from the polar regions, in the shape •f a reaction. This current bathes elevated districts' with its glacial 'waves, and is yet so capricious as to pass over some valleys; freezing one field, while a neighboring one escapes. Science cannot explain this.. It is well known that the vicinity of icebergs is indicated by a " diminution ot temperature. M. Mitchel, in the annual meeting of■ -savants now being held,-''suggests, that to prevent shipwrecksvOwing jto collisions with icebergs, Transatlantic steamers . ought to carry submerged, eleotro-thermometers, that would communicate with - an alarm bell, when a certain temperature would be revealed.

OK VACCINATION. -M. Feltz lias conducted a series of experiments to discover the nature of the poisonous principle in putrefied blood. Dogs innoculated with infected blood, invariably become ill, frequently dying between the third and eighth day after the operation. He "tried every means for perfectly filtering the .diseased' blood, but could never deprive it of its virulent properties; even when preserved in an exhausted receiver, or in pure oxygen gas, the animalcu'lae remained still present, their vitality being suspended, but never dostroyed.- He is satisfied the venomous principle is not a gas. The Academy of

Medicine corroborates-the uncertainty which exists, relative to the preservative action of vaccine matter ; its duration is very variable, exceeding six years and sometimes not as many months. M. Hervieu explains, that the pock is but the coatre-poison of small-pox, and when the latter is. stronger, the former rests without effect. Vaccination is not a specific against small-pox—it is only a useful precaution, but not a certain preservative, and re-vaccination implies a a chance more against disease. The constitution can be refractory both against vaccination and small-pox, and the latter can attack us, not only if wo have been vaccinated, but if our organism has resisted taking the pock. An individual even may escape the malady though living in an atmosphere full of its miasma, but contract it when the malady^isQm decline. Is it possible to find a preservative more efficacious than the Jenner system? D"r Lombard of Geneva, and Dr Pap'lland of Paris, though vaccinated as usual, innoculated themselves several times with the virus of small-pox itself, and attribute to this cause their escape from the small-pox plague. This system, however, increases the centres of infection. During an epidemic of small-pox, people should not rock themselves in any delusion as to enjoying immunity, from the disease, rather it is the more incum- j bent, thenj on perions of all ages, to have themselves re-vaccinated.