DR. REID'S ILLUSTRATIONS OF VENTILATION.

Da. REID is the celebrated chemist, who has achieved the miracle of purifying the very corrupt atmosphere of the House of Com- mons ; and who tried, though less successfully, to dissipate by fans, or endow with wholesome properties, the deadly malaria of the Niger, when BUXTON, RUSSELL, PEEL, and Co., sent so many un- fortunates to a grave, instead of to the glory of " civilizing Africa." In the volume before us, Dr. REID not only narrates the means by which he ventilates the Houses of Parliament, and the apparatus be contrived for the steamers employed on the Niger Expedition, but he expatiates on the lamer subject of the " air we breathe " and hear by. His volume, otcourse, contains an exposition of the principles on which the art of ventilation is founded, as well as a description of the different modes by which these principles may be applied, under favourable or adverse circumstances. The Doctor also illustrates in detail the cognate branches of chemical science, which may aid or mar ventilation ; as the action of heat, moisture, the different gases, and so forth. But he goes yet further. Does the reader wish to study the art of oratory, or of constructing rooms for orators—there is an exposition of the laws of sound, with the best method of practically applying them. If he wishes to• warm his house—a division of the book is devoted to the different modes of heating, by the open grate, the stove, steam, and hot water ; with some useful hints touching that domestic nuisance, only second to a scolding wife, a smoky cbitnney. Is light his aim— here he may have the rationale of oil, gas, and candles. Eschewing the poet's maxim, "where ignorance is bliss 'tis folly to be wise," does any man wish to know the dangers that compass him round about as he walks at noon-day through the crowded city—Dr. Ram is the writer to open his eyes to the evil that enters his mouth, from noxious exhalations and vapours, originating with drains, burial- grounds, manufactories, and what not. Is a congregation listless under the sermon, or does a preacher fail in producing that effect which he is self-conscious his oratory ought to achieve—consult Dr. REID'S book, and then Dr. REID. He, testing the air rather titan the eloquence, sees growing heaviness in the audience with the growing heaviness of the atmosphere. The exhortations of the divine grow flat, if not cold ; " the pulpit, drum ecclesiastic," is struck with a force continually diminishing as the climax rises, or rather as it should rise ; and the mass of the congregation exhibit signs of reaching the condition of the competitors in the Dunciad, where even the most pert and loquacious sunk into slumber under the effect of the soporific readings. To the unchemical observer the congregation would illustrate the depravity of mankind without needing the enforcement from the pulpit : but Dr. REID, subjecting the air to analysis, knows better—it is the corruption of the atmo- sphere, not of human nature, which has produced the melancholy scene. Let a disciple of ventilation take the matter in hand, how soon would the face of things be changed! As old air cannot be expelled without new, his first care would be to introduce fresh at- mospheric air into the lowest part of the church—not in currents, to give colds, but through an infinite variety of small apertures in convenient places, so as to be equally but imperceptibly diffused; and if need be, he would first carry it through an anteroom or equalizing chamber, where its temperature would be controlled. The next step is to provide for the egress of the foul air ; which is done by perforating the ceiling in a sufficient and convenient man- ner; and as the heated air naturally ascends, this is in many cases sufficient without resorting to artificial means. Still there is a further stage. When the corrupted air has passed through the ceiling into the loft, little is gained if it impinges upon the roof, which stops its egress : a funnel or chimney towering upwards is therefore reared, into which the air passing from the body of the church is conducted, and an ascending impetus given if need be by a fire or other means. Then what a change comes o'er the of the scene 1—the audience, throwing off their dulness, are intent ; the orator is not himself again, but what he never was before ; the energy of the open-air preacher is fairly attained, and the churchyard and dinner-tables ring with " What a powerful discourse we had this morning !"

It may be surmised that "nothing like leather" is the text of Dr. REID; and, like moat enthusiasts, he not only demands for his topic a greater attention than the many pursuits of life will permit any single subject to receive, but we think he does not, in a medical sense, sufficiently allow for the power of adaptability in nature, which lessens the mischiefs of bad ventilation, and will prevent good, we fear, from realizing the golden age of Dr. Ram's fancy. Readers may also think that several of his ideas are impracticable under any circumstances, if not impossible. But this rather arises from mankind not being willing to adapt all their habits to one ob- ject of regimen, than from any inherent impracticability. This taint, however, is almost inseparable from a new discoverer, zealous in his theme ; and it does not affect the scientific conclu- sions or the admirable clearness of his style. The expositions of ventilation, either in relation to public or private buildings, as well -as to mines and ships, are, of course, original ; as is the applica- tion of the principles on which they rest, if not the principles themselves. The various chemical facts, and the different parts of chemical science introductory to the great theme, though not new, are apt and very clear, and often have a novelty from the mode of their use. Dr. REID is also entitled to the merit of possessing the reader with the subject of ventilation. Should any one peruse this book and enter a crowded room, we think he will glance his eyes towards the ceiling, and think or say, " The builder knew nothing of ventilation : all that space now worse than useless could have been used to carry off this air which is oppressing me : nay, these ornamental panels, which could have concealed any perforation, are as solid as the man's own skull."

Any thing like a just idea of this work can only be attained by studying it ; but a few extracts will indicate the really amusing character of Dr. REID'S style and manner of treatment.

VENTILATE THE SOLDIER.

Among those engaged in special pursuits, where particular clothing is re- quired from the circumstances under which they are exposed, the porosity of the clothing cannot be too specially studied. A soldier encased in a metallic helmet, in a cuirass, and the rest of his body iu leather, every pore of which is obstructed, affords a good example where the diffusion of the skin is retarded in an extreme degree, and increased duties thrown on the lungs and face ; the latter often appearing suffused with perspiration, at times when with a more porous dress nothing of the kind would be observed.

THE PERFECTION OF A GRATE.

A. front made of the lightest possible iron bars that may be considered lasting, and placed on the level of the floor, that the floor and feet may have the fullest benefit from the radiation. Placed at a higher position, it has in some respects the advantage of throwing the heat in a different manner; bat it never then affords the personal comfort which a low fire presents to those who may wish to be sensible of the influence of its rays,—a practice which, although not to be recommended to pass into a habit, is too agreeable not to be resorted to when the system has been chilled. It is not in general suffi- ciently remembered, that the great object, with all ordinary fires, is to heat the floor. If this be accomplished, it moderates the severity of cold air there, and the upper portion of the apartment is warmed by the ascending currents that

are immediately developed.

Where iron is used in large quantity around an open fire, it robs so much heat from it, and communicates so large a quantity, by conduction, to the current of air passing up the chimney, that it rarely burns brilliantly. Every portion of metal that may in any way be dispensed with, proves advantageous in an open fire.

SIMPLICITY OF SCIENCE.

In many manufactories, materials are evolved, which if subjected to the - action of an elevated temperature before they pass into the open air, are

rendered entirely innocuous, or at all events produce no offence beyond that developed by the ordinary products of combustion. Thus, at Burntisland, a small sea-port about ten miles from Edinburgh, a manufactory of whale-oil from blubber was carried on not long ago, where all the noxious matter usually evolved was completely destroyed by being drawn through red-hot cinders supplied freely with air at the same time ; bat when this arrangement was not .in force, the offensive odour from the manufactory was perceptible at the dis- tance of miles, in the direction of the wind. Similar arrangements have long been applied by M. D'Arcet of Paris to the melting of tallow, and other opera- tions ; and might, with much advantage, be more generally introduced.

TROUBLES WITH THE HOUSE OF COMMONS.

In directing the ventilation, great difficulty is often experienced in ascertain- ing the feelings of the Members. They necessarily fluctuate with every change of circumstances in the state of the internal or external atmosphere that is not immediately controlled, independent of the extreme diversity of temperament that may be expected to prevail where so many are assembled in

the same apartment. • •

Attendants on the ventilation take the temperature periodically during the sittings, and are constantly ready to receive instructions as to the alterations required when they may not have anticipated them, though this they are in general enabled to effect. But as no one can ever be an exact judge of an- other's feelings, and from the great diversity of requests at times communicated to them, and the fact that extreme constitutions are necessarily most prone to demand changes, while their indications are less likely to conduce to the ge- send comfort, it is not nnfrequently difficult for them to decide as to com- plaints: communications, therefore, as to the ventilation, are usually addressed to the Sergeant-at-Arms ; whose knowledge of the general expression of opi- nion is always a safer guide than that of individual Members. In some cases, where the debates in both Houses have continued fur a long period, and the fluctuations have been great both in the state of the weather and of the num- bers attending. I have occasionally, in studying details as to the action of the ventilation, made, with advantage, from fifty to one hundred variations in the quantity or quality of the air supplied in a single night.

PARLIAMENTARY HINTS OR FACTS.

Some constitutions differ so much from others in respect to the air which is most suitable for them, and are so much affected by variations in the tempera- ture and moisture of the air that may he almost inappreciable by others, that, where it may be requested, I have certainly been led to entertain the opinion, that any Member who may have specially to address the House should have some preference, at least, in controlling the temperature and the ventilation when he is so engaged. The temperature may always be advantageously increased, and the velocity diminished, before the usual dinner-hour. dfter dinner, other circumstances being the same, the temperature should be diminished, the velocity increased, and the amount of moisture in the air re- duced, when practicable.

Daring late debates, as they advance to two, three, four, and five in the morning, the temperature should be gradually increased; as the constitution becomes more exhausted, except in cases where the excitement is extreme.

CORRUPTIONS ABOUT THE HOUSES.

When a great fall takes place in the barometer, the drains, the river, and the surface of the ground, often exhale bad air to such an extent that the entire atmosphere on every side of the Houses is loaded with impurities. Gas-liquor on the surface of the river is an occasional source of offence. I noticed it at times covering the surface of the water for nearly a mile in length, and floating past the louses of Parliament. It is familiarly known to the ' watermen by the name of Blue-Billy. Emanations from the grave-yard at St. Margaret's Church are occasionally very offensive. They have been the subject of complaint more especially by Members attending the Committee-rooms oppo- site. Of seven different individuals whom I requested to inform me of any emanation which they might perceive arising from the grave-yard, one stated that he had never noticed any thing offensive, though he had passed through-it almost daily for years. The second stated, that at one period, for about a month during the summer, the emanations were very offensive. Four others noticed them frequently. The last, who is at present engaged at the Houses of Parliament, has noticed them repeatedly. On one occasion, he informed me that he suffered severely from headache and sickness for several days, after passing through this churchyard. Its effects caused him to lie down several times in the afternoon, and he was unable to take his usual refreshment. He had not, consequently, passed through it since, preferring to go round about for the last several months.

The smell from gas-works on both sides of the river occasionally affects the atmosphere on every side of the House. The entire surface of the street has occasionally been found to present a sur- face of decomposing impurities not capable of being easily controlled but bythe action of lime-water.

In calm weather, the smell of tobacco occasionally accumulates in the neigh- bourhood. On one occasion, about fifty coachmen were counted smoking 'at the same time.