Dr. Smith on the Air inspired during the Day and Night. 547 
‘The paper concludes with a summary of the principal results ob- 
tained and a series of deductions, applicable especially to the solution 
or elucidation of hygienic questions. From the former the following 
facts are extracted :— 
The total quantity of air inspired in 24 hours (allowance being 
made for intervals amounting altogether to 40 minutes, during 
which it was not recorded) was 711,060 cub. ins. ; or an average of 
29,627 cub. ins. per hour and 493-6 per minute. The quantity was 
much less during the night than during the day. There was an 
increase as the morning advanced and a decrease at about 84 30! P.M., 
but most suddenly at about 11 p.m. During the day the quantity 
increased immediately after a meal, and then subsided before the 
next meal; but in every instance it rose again immediately before a 
meal. The rate of frequency of respiration generally corresponded 
with the quantity, but the extremes of the day and night rates were 
greater. The period of greatest parallelism was between tea and 
supper. Anincrease was occasioned by one meal only, namely break- 
fast. The average depth of respiration was 26-5 cub. ins., with a 
minimum of 18-1 cub. ins. in the night, and a maximum of 32:2 cub. 
ins. at 1" 30' p.m. The mean rate of the pulse was 76 per minute, 
the minimum at 3" 30'a.m., the maximum at 8 45! a.m.; the dif- 
ference being more than one-third of the minimum rate. 
Sleep came on in two of the series of continuous observations, and 
the time of its occurrence was also that of the lowest quantities of 
air inspired. 
The amount of breathing was greater in the standing than in the 
sitting posture, and greater sitting than lying. It was increased by 
riding on horseback, according to the pace, also by riding in or upon 
an omnibus. In railway travelling the increase was greater in a 
second- than in a first-class carriage, and greatest in the third-class 
and on the engine. An increase was also produced by rowing, 
swimming, walking, running, carrying weights, ascending and de- 
scending steps, and the labour of the tread-wheel; and in several of 
these cases the rate of increase was determined for different degrees 
of exertion used. Reading aloud and singing, and the movement 
recommended by Dr. Hall for restoring suspended respiration, in- 
creased the quantity ; bending forwards whilst sitting, lessened it. 
The quantity of inspired air was increased by exposure to the 
heat and light of the sun, and lessened in darkness. Increase and 
decrease of artificial heat produced corresponding effects; and the 
depth of respiration was greatly increased by great heat. An in- 
crease in quantity was caused also by cold bathing, and sponging, 
and the cold shower-bath ; by breakfast, dinner, and tea—when tea 
actually was taken, but when coffee was substituted there was a 
decrease. Supper of bread and milk also caused a decrease. Milk 
by itself or with suet caused an increase. 
An increase was obtained with the following articles of diet, viz. 
eggs, beef-steak, jelly, white bread (home-made), oatmeal, potatoes, 
sugar, tea,rum(loz.). The following caused a decrease, viz. butter, 
fat of beef, olive oil, cod-liver oil, arrow-root, brandy (1 0z. to 1% 0z.), 
and kirchenwasser. Ether (}drachm) increased the quantity and 
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