296 



NATURE 



\Feb. II, 1875 



Benzine. 



Blue part of gas Blue pait ofpeti-olc 



ilan 



Beginning of ist band... 563*2 s62"9 — 



End — 537 "",.,,. 



Beginning of and band.. 5164 siG'i 515-5 bright Ime. 



512-5 broad bright ^^^.^ f^j^^ band. 



End of and band — lox 



Beginning of 3rd band... 474'2 473'^ 

 Brightest part 

 End 



very delicate 

 473 iiie. 



•7' '2 — ••72;S faint bands. 



— 464 4*^0 o 



,.„ middle of a ,„ , middle of broad 

 t3fiS band. ••"' faint band. 



430*0 broad line. 430S bright Hoe. 

 From this table it appears that the beginning of the bands of 

 each comet correspond, but that the brightest parts of these vary 

 in position. For comparison with other comets the brightest 

 parts of the bands are given : — 



Comet I., 



Comet, 



554 

 512 



1st band 557 557 555 



2nd band 511 513 5'2 



3rd band — 472 473 4^9 



The remainder of the paper on the change of form consists of 

 daily notes referring to drawings and giving measurements of the 

 comet. The nucleus appears to have changed its shape from 

 round to oval and other lorms.— In No. 2,019 Dr. Luther gives 

 an ephemeris for Planet (104) Clymene, which has not been 

 seen since 1S6S.— Dr. Iloletschek and Dr. Lutlier give position 

 observations ol comets and minor planets made last year. — 

 G. W. Hill sends a note on a long period of irregularity of 

 llestia, arising from the action of the earth, and its applica- 

 tion to ascertain the value of the solar parallax. — ^J. Palisa writes 

 to say that he has discovered Clymene ; he also saw Dione and 

 Altha:a again. — Winnecke mentions the discovery, by Borrelly, 

 of a comet, position December loth : Decl., + 39* 49' '5 ; R.A., 

 i6h. 4m. 65s. 



SOCIETIES AND ACADEMIES 



London 



Royal Society, Jan. 2S.— " On the Theory of Ventilation : 

 an attempt to establish a positive basis for the calculation of the 

 amount of fresh air required for an inhabited air-space," by 

 Surgeon-Major F. de. Chaumont, M.D., Assistant Professor of 

 Hygiene, Army Medical School. Communicated by Prof. 

 Parkes, M.D., F.R.S. 



In a paper in the Edinbiiroh Medicai Journal for May 1S67, 

 the author adduced some results to show that the evidence of the 

 senses might be employed (if used with proper care and precau- 

 tions) as the ground-work' of a scale, and gave a short table of 

 the amounts of respiratory impurity (estimated at COo) which 

 corresponded to certain conditions noted as affecting the sense 

 of smell. 



It is generally admitted that it is organic matter that is the 

 poison in air rendered impure by the products of respiration. 

 It is also admitted that it is the same substance that gives the 

 disagreeable sensation described as "closeness" in an ill- 

 ventilated air-space. Although the nature of the organic matter 

 may vary to a certain extent, it will be allowed that a condition 

 of good ventilation may be established if we dilute the air 

 sufficiently with fresh air, so that the amount of organic matter 

 shall not vary sensibly from that of the external air. Observa- 

 tions, however, as far as they have gone, seem to show that the 

 amount of organic impurity bears a fairly regular proportion to 

 the amount of carbonic acid evolved by the inhabitant in an 

 air-space ; and as the latter can be easily and certainly deter- 

 mined, we may take it as a measure of the condition of the 

 air-space. If we adopt as our standard the point at which there 

 is no sensible difference between the air of an inhabited space 

 and the external air, and agree that this shall be determined by 

 the effects on the sense of smelly our next step is to aseertain 

 from experiment what is the average amount of COj in such an 

 air-space, from which we can then calculate the amount of air 

 required to keep it in that condition. All the author's results 

 have been obtained in barracks and hospitals. 



The plan followed in all was to take the observations chiefly 

 at night, when the rooms or wards were occupied, and when 

 tires and lights (except the lamp or candle used for the observa- 

 tion) were out. On first entering the room from the outer air 



the sensation was noted and recorded just as it occurred to the 

 observer, such terms as "fresh," "fair," "not close," "close," 

 "very close," "extremely close, " &c. being employed. The 

 air was then collectel (generally in two jars or bottles, for con- 

 trolling experiments), and set aside with lime-water for subse- 

 quent analysis, and the temperatures of the wet and dry bulb 

 thermometers noted. About the same time samples of the 

 external air were also taken, and the thermometers read. In 

 this way any unintentional bias in the record of sensations was 

 avoided, and this source of falUcy fairly well eliminated. 



Although the records of sensation are various in terms, the 

 author has thought that they might be advantageously reduced 

 X.0 five orders or classes, each of which he characterises by one 

 or more appropriate terms in common use. 



He then proceeds to give an analysis of the results of his 

 observations on the case of each order, from which he draws 

 the following conclusions : — 



In order No. I, "Fresh," &c., a condition of atmosphere 

 not sensibly different from the external air, the conditions which 

 are those of t^ood ventilation are the following : — 

 Temperature about 63° Fahrenheit. 

 Vapour shall not exceed 47 grains per cubic foot. 

 Carbonic acid shall not exceed the amount in the outer air by 

 more than o"2000 per 1000 volumes. 



No. 2. — " Rather close," &c. A condition of atmosphere in 

 which the organic matter begins to be appreciated by the senses, 

 and the ventilation ceases to hs i^ood : — 



Vapour in the air exceeds 47 grains per cubic foot. 

 COo in excess over outer air, ratio reaching 0*4000 per looo 

 volumes. 



No. 3. —"Close," &c. The point at which the organic 

 matter begins to be decidedly disagreeable_to the senses, and the 

 ventilation begins to be decidedly bad :— 

 Vapour reaches 4'g grains p^er cubic foot. 

 Carbonic acid in excess over outer air to the amount of 

 0'6ooo per looo volumes. 



No. 4. — "Very close," &c. Thepoint at which the organic 

 matter begins to be offensive and oppressive to the senses, and the 

 ventilation I'lvy to</." — • t."; . 



Vapour reaches 5 "oo grains per cubic foot. 

 Carbonic acid in excess over outer air reaches o'Sooo per 

 1000 volumes. 



No. 5. — "Extremely close," &c. The maximum point of 

 differentiation by the senses : — 

 Vapour 5'loo grains per cubic foot. 



Carbonic acid, in e.xcess over the amount in the outer air 

 beyond, o'85co per 1000 volumes. 



It will at once be seen that the figures in No. 5 differ but 

 little f om those in No. 4, and that the probable limit of 

 differentialion by the senses is readied in No. 4. The number 

 ot recorded observations in No. 5 is also very few comparatively ; 

 and the author thinks it would therefore be better to group the 

 two together thus : — 



Nos. 4 and 5 combined, being the probable limit of possible 

 differentiation by the senses. 



1. Temperalitre. — In Irlie outer air 5i"'43> '" ^^ inhabited 

 air-spaces 65°'I2, or a mean difference of I3°'69. 



2. Vapour and Humidity. — The vapour in the outer air was 

 3729, inside 5'loS, or a mean difference of f37g grain, cor- 

 responding to a lowering of relative humidity of 8 '92 per cent, 



3. Carbonic Acid.— \\\ the.'outer air 0-3928, in the inhabited 

 air-spaces f246i, or a mean difference due to respiratory 

 impurity of o'8533, the range for probable error of result 

 being between 0-8717 and 0-S349. 



We may therefore say that when the vapour'* reaches 5-100 

 grains per cubic foot, and the CO^ in excess o-Sooo volume 

 per 1,000, the maximum point of differentiation by the senses 

 is reached. 



The author then shows that^there is a regular progression as 

 we pass from one order to another, 



lie then proceeds to give a largff number of tabular state- 

 ments, calculations, and ratios, his practical conclusion being 

 that the experimental data already quoted fairly justify the 

 adoption of the following 



Conditionsais the Standard of good I 'entilation. 

 Temperature (dry bulb) 63° to 65° Fahrenheit. 

 ,, (wet bulb) 58° to 61° „ 



* It is to be understood that the amounts of vapour stated in liiese cases 

 arc in reference to a mean temperature of about 63 F, 



