The divine wisdom of the Founder of the sacrament of confession is most signally vindicated in these few pithy words, which we leave to the reflection of the reader.
In the concluding portions of his work the author gives some most interesting statistics of the growth and proportions of infidelity and scepticism in our country, of the results of Catholic and Protestant missions among the heathens, and of the state of religion throughout the world. These make his work more complete, and will be received gladly by many who have not had their attention called to these facts before. We think they add very much to the completeness of the work, and it was a happy idea of the author to put them in. Dr. Marcy's book ought to do a great deal of good, and we do not doubt that it will. The number of unpalatable truths told in it, and the direct, incisive way in which they are told, have provoked and will provoke much unfavorable comment. Every effort will be made to discredit it. It will be called vituperative, false, and calumnious. Its truth—and Dr. Marcy has taken good care to back up all his assertions with the best of evidence—is the best refutation of all such accusations. We find every day all sorts of false and calumnious statements, circulated without a particle of proof, in the books, the periodicals, and newspapers of the land, against the persons and the doctrines we hold most dear. It is of little use to reply, the lie is circulated and the reply is left unnoticed. Our opponents take all their representations of our doctrines and practices, at second hand, from the writings of our deadliest enemies, and never think it worth while to verify their statements by looking at the statements of our own councils and standard writers. This treatment is absolutely unfair, and the most respectable are blind to its meanness, where we are concerned; but let the Catholic writer tell the outspoken truth and back it up by genuine testimony of their own writers and partisans, and the cry is at once raised of "calumnious, incendiary, malicious," etc. etc. It will be easier to raise a cry against this book than to answer its statements. When Marshall published his history of Christian Missions, with its thousands of references to the most unsuspected Protestant witnesses, we looked for a reply which would be something more than merely throwing dust in the eyes of the public, but we have looked in vain up to this time; its statements have never been answered. So we feel sure it will be with this book. It may be called hard names, but it will not be seriously answered. If it will be thoughtfully read, we shall feel content. It will then, at least, be answered, as we prefer to see all honest representations of the truth answered, by the removal of prejudice, the correction of many false ideas which prevail concerning our holy faith, and the consequent desire, which we pray may arise in not a few sincere minds, to examine more fully into its character and the grounds of its claims to be the true religion of Jesus Christ.
From Chambers's Journal.
Thermometers.
An ordinary thermometer consists, as everybody knows, of a glass tube, fixed to a scale. This tube contains a fine bore, and has a bulb blown at one extremity. Some liquid, generally mercury or alcohol, is introduced into the tube, the air is driven out, and the tube is sealed. The quantity of fluid, say mercury, admitted into the tube is so regulated that at common temperatures the bulb and a portion of the bore are filled. The remainder of the bore, which is empty, affords space for the mercury to rise. This arrangement renders very perceptible the alterations in the volume of the mercury due to changes of temperature, a very slight increase or diminution of volume causing the mercury to rise or to fall appreciably in the fine bore. After sealing, the scale has to be adjusted to the tube, and the instrument is complete.
Thermometers of the most accurate make are called standard thermometers. In their manufacture, numerous precautions are necessary from the very outset. Even in so simple a matter as the choice of the tube of glass much care is requisite. The bore has to be tested, in order to ensure that it is of uniform capacity throughout. It is found that tubes, as they come from the glass-house, contain a bore wider at one extremity than the other. The bore is, in fact, a portion of a very elongated cone. In a hundredweight of tubes, not more than half a dozen or so can be picked out in which the bore is perfectly true. The bore is tested in a very ingenious though simple manner. A bulb is blown, and a very small quantity of mercury is admitted into the tube about as much as will fill an inch and a half of the bore. By alternately cooling and heating the bulb, this delicate thread of mercury is driven from one end of the tube to the other, and during this process its length is carefully measured in all parts of the tube. Should the length of the mercury alter in various situations, it is evident that the capacity of the bore is not uniform throughout, and the tube must be rejected. In blowing the bulb, an elastic ball, containing air, is used. The ordinary method of blowing glass bulbs by means of the breath is found to cause the introduction of moisture into the tube.
The size of the bulb has next to be considered. A large bulb renders the instrument slow in its indications of change, owing to the quantity of mercury that has to be acted on. On the other hand, if the bulb is too small, it will not contain sufficient mercury to register high temperatures, unless the bore is exceedingly fine.
The shape of the bulb is of importance. Spherical bulbs are best adapted to resist the varying pressure of the atmosphere; while cylindrical bulbs expose larger surfaces of mercury, and are therefore preferred for more delicate instruments. Various plans have been suggested in order to obtain thermometers of extreme sensitiveness for delicate experiments. Some have been made with very small thin bulbs, to contain a very small quantity of mercury; but in these the indicating column is generally so fine, that it can only be read by the aid of a powerful lens. Instruments have been contrived with spiral or coiled tubular bulbs; but the thickness of glass required to keep these in shape nullifies the effect sought to be obtained—namely, instantaneous action. Messrs. Negretti & Zambra, the well-known meteorological instrument-makers, have recently succeeded in constructing a thermometer which combines sensitiveness and quickness of action, and which presents a good visible column. The bulb of this thermometer is of a gridiron form. The reservoir is made of glass, so thin that it cannot be blown; it can only be formed by means of a spirit-lamp; yet its shape gives it such rigidity that its indications are not affected by altering its position or by standing it on its bulb. The reservoirs of the most delicate of these instruments contain about nine inches of excessively thin cylindrical glass, the outer diameter of which is not more than the twentieth of an inch, and, owing to the large surface thus presented to the air, the indications are positively instantaneous. This form of thermometer was constructed expressly to meet the requirements of scientific balloon ascents, to enable the observer to take thermometric readings at precise elevations. It was contemplated to procure a metallic thermometer; but, on the production of this perfect instrument, the idea was abandoned.
The shape and size of the bulb having been determined, the workman next proceeds to fill the tube. This is effected by heating the bulb while the open end of the tube is embedded in mercury. Upon allowing the bulb to cool, the atmospheric pressure drives some mercury into the tube. The process is continued until sufficient mercury has entered. The mercury used in filling should be quite pure, and should have been freed from moisture and air by recent boiling. It is again boiled in the tube after filling; and when the expulsion of air and moisture is deemed complete, and while the mercury fills the tube, the artist dexterously removes it from the source of heat, and at the same moment closes it with the flame of a blow-pipe. It sometimes happens that in spite of every care a little air still remains in the tube. Its presence is detected by inverting the tube, when, if the mercury falls to the extremity (or nearly so) of the bore, some air is present, which, of course, must be removed.
The thermometer, after being filled, has to be graduated. Common thermometers are fixed to a scale on which the degrees are marked; but the graduation of standards is engraved on the stem itself, in order to insure the greatest possible accuracy. The first steps in graduating are to ascertain the exact freezing-point and the exact and to mark on the tube the height of the mercury at these points. The freezing-point can be determined with comparative ease. Melting ice has always the same temperature in all places and under all circumstances, provided only that the water from which the ice is congealed is pure. The bulb and the lower portion of the tube are immersed in melting ice; the mercury descends; the point where it remains stationary is the freezing-point, and is marked on the tube.