"Sound, by being condensed in a tube, is rendered audible at a great distance; therefore, by means of pipes, which confine the sound, the voice may be heard considerably beyond its natural limits. Hence have arisen various deceptions. The condensation of sound has similar effects with the condensation of light, in increasing the natural powers. When a person speaks in a trumpet, the large waves formed at the wide end of it are compressed at the axis by the reflecting surface inside the tube; and, passing to the ear in that state, a greater effect is produced than by the usual mode of conveyance. If two trumpets are fixed in situations opposite to each other, even at the distance of forty feet, the sound of the lowest whisper spoken at the mouth of one of them, will pass to the other, and may be distinctly heard. The similarity between the effects of condensed light and sound is evidently proved by experiment. If we place two concave mirrors, or surfaces, made of glass, or any reflecting substance, at the opposite ends of a large apartment, and a person stand at the focus of one*, and another person at the focus of the other, they may converse in the lowest whisper, which will be to each perfectly au

dible."

The Fifth and Sixth Lectures are devoted to the illustration of hydrostatics, hydraulics, and the motion of fluids in general, of which the following is a fair specimen of the diverse facts and observations communicated in the author's familiar and desultory manner:

"The effects of capillary attraction, by which moisture is conveyed through the interstices of wood, &c. are employed by mankind in various mechanical operations, particularly in dividing substances with greater ease and safety than by percussion. A very striking use of this property presents itself to my recollection, as employed in dividing mill-stones. The stones used for this purpose are first formed into cylinders of considerable length; to separate these into the proper proportions, indentures are cut at suitable distances on the outer surface of them in a circular form, into which are driven wedges of dry wood. By the application of water to these wedges, the cylinders are divided; for the fluid is drawn to the other extremity of the wood by the capillary attraction, which causes an expansion that splits the stone asunder. Capillary attraction is concerned in most of the operations of nature; for nutriment is conveyed through these fine tubes to all the parts of vegetable substances and animal bodies. Many familiar effects arise from corpuscular attraction; as, oil supplying the wick of a lamp, water dividing sugar or salt: in a word, all the pores and interstices of bodies are capillary tubes, which imbibe fluids, efflu via, &c."

The Lecture on Magnetism is the most intelligible, satisfactory, and perhaps complete, that we have seen on this hitherto undefinable subject. The author has evinced much judgment and good sense in omitting all the visionary speculations relative to magnetism, with

"The focus of a concave mirror is at one-fourth the diameter of a sphere of which the concavity of the mirror is an arc.”

NO. CII. VOL. XXV.

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which

which the public has been so long idly amused, and has confined herself to a clear and complete statement of all the known phenomena. The facts relative to the variations and dip of the magnetic needle are concisely detailed, and Mr. Canton's observations on the slight variations or deviations of the needle in the morning, noon, and night, occasioned by the solar heat, as he supposed, are particularly mentioned. We could have wished, indeed, that Mrs. Bryan had given some account of the attempts made to identify the magnetic with the electric power, as they are much more similar in their characters than water is to oxygen and hydrogen, of which it is entirely coinposed.

Electricity occupies the Eighth and Ninth Lectures, which the author seems to have treated con amore. "Of the two theories of clectricity which have obtained the greatest share of approbation with philosophers, one is called Ellis's, being his idea as established by Volta and Mr. Atwood; the other, Franklin's, though Dr. Watson first intimated the opinions which were afterwards digested and established by Dr. Franklin:" the leading principles are given without deciding in favour of either. The fair Lecturer proceeds to relate experiments which in general are applicable to both theories, and which render it very difficult, if not impossible, "to wholly reject either of them." She also proposes several shrewd conjectures of her own, relative to the power of electrics, which she supposes to be only that of having a particular capacity for accumulating or attracting the electric fluid from the atmosphere, and surrounding bodies. The experiments of Mr. Symmer, on black and white silk stockings, are also stated, in which it appears, that a black and white silk stocking, warmed, and drawn on the leg over each other, and taken off without separating them, became electrical, and adhered together with a "force that required sixty (six) times their own weight to part them." Trying two pairs of stockings, one black, and the other white, each repelled its fellow, and attracted the contrary one. Two black stockings did not exhibit electricity. Our author also gives some very good directions for guarding against danger in a thunder-storm. An imperfect sketch of Galvanism is likewise introduced, but the Lecturer forbears to dwell on this subject, for the truly Shandean reason, which is unworthy of her, that "many cruel experiments have been tried in this science!" Such sentiments she may consider as honourable proofs of her sensibility, but we cannot hesitate in affirming, that they are the very antipodes to those of genuine humanity. According to such preposterous affectation, it were more humane to suffer a patient to die of a fractured limb, than to save his life by amputation.

. The Tenth, Eleventh, and Twelfth Lectures are on optics, and the nature of vision; and notwithstanding the dryness and difficulty of the subject, there are very few readers who will not be amused by the curious experiments and observations here rendered familiar to the meanest capacity. The following observations on light occur before entering on the subject of colours:

"We

"We are now far advanced in the consideration of light, and the ence of optics; having, by ocular demonstration of certain results, in. red with certainty many important facts: such as, that the particles of ht are inconceivably small, and move in a rectilinear direction with tonishing velocity-that a ray of light, radiating from a centre, diverges its progress-that the density of light at certain distances depends on its sity at the radiating point, and its distance from it, and this difference ing also in proportion to the squares of its distance from the luminous int-that the angle made by a ray of light in its reflection, is always ual to its angle of incidence; and hence, when the angle of incidence is und, the angle of reflection is likewise ascertained-that concave mirrors ollect parallel rays, and cause them to meet in a focus by reflection; and at the focus of a concave mirror is at the same distance from its sur ce as the focus of a convex lens-that the heat and light of a luminous ody reflected from a concave surface, are as much increased at that focal oint, as that point exceeds the surface of the lens; the same as happens in egard to the surface and focus of a convex lens by refraction, which auses the rays of light at the focus of very large concave mirrors, and onvex lenses, by being greatly accumulated at their foci, to burn almost dl bodies subjected to their influence. We have also contemplated the cuious organization of the eye, so far as its optical effects are known; and discovered, that the construction of optical instruments depends on the known properties and capacities of the coats and humours of this useful and ornamental organ of the animal creation.”

On the preservation of the sight, the following reflections are original and important:

"To render our knowledge on this subject (the science of vision) in some degree serviceable to mankind, I will state a few particulars worthy of attention. Long-sightedness arises from a depression of the lenses that compose the organ of sight, which is occasioned by a deficiency in the hu mours of the eye, and a rigidness of the muscles that regulate its movements. In order to retard and counteract as much as possible the inconve niences of this natural decay of sight, it is necessary, as we advance in years, to accustom ourselves to look at objects as near as we conveniently can, and to employ the eyes moderately in viewing attentively a variety of objects at different distances. To avoid the impressions of a very strong light, and the sudden transition from darkness to an opposite extreme, frequently open and shut the upper lid, in order to diffuse a fluid that is intended to lubricate the eye. This act is usually performed instinctively, without our attention; but as some persons, constantly occupied in contemplating very small objects, are apt to get a fixed position of the eye, I deem this caution necessary: I have myself experienced the inconvenience attending negligence in this particular, when painting small objects on ivory; for after sitting many hours, earnestly contemplating the performance, a painful sensation in my eyes has been produced. The muscles of the eye grow stronger by moderate exercise, and are enfeebled by disuse; and the coats of the eye are rendered flexible by use, and become rigid by inactivity."

The facts and illustrations of the nature and influence of colours

are no less curious and interesting, but our extracts have already c tended to an unusual length. The Thirteenth and last Lecture c braces astronomy, and will not detract from the fair fame which th author has honestly acquired by her former labours in that sublimi science.

Before concluding our observations on this elegant volume, how ever, we must beg leave to fulfil another, and not the least important part of our duty to the public, namely, to examine the moral prin ciples here inculcated. The author (mistress of a very respectables boarding school on Blackheath), with great propriety, gives a con cluding admonitory Address to her fair pupils on the moral and politica conomy of their future lives. The primary object of these Le tures, we are told, and the work bears internal evidence of the fac was to support religion, and superinduce habits of pious adoration fo... the Supreme Being in contemplating his works. The merit of such a design is unequivocal, and we do not hesitate to say, that its execu tion is highly praiseworthy and agreeable. In this Áddress, the lead ing and essential doctrines of religion, and its offices, are first laid. down, with great perspicuity, as the source of all knowledge and virtue; next, the "moral duties in every relation of female life-25 children, sisters, friends, wives, mothers, and associates." Jus tice, prudence, temperance, and fortitude," we are told, are the basis of all these duties." As children, be obedient and grateful to your parents; as friends, faithful and reasonable; as sisters, affectionate;" and,

"When wives, consider the solemn oath pledged before God, and strictly obey its mandates. Let cheerful acquiescence evince your affec tion towards your husband. Be the softener of his cares-the sympathizer in all his anxieties; and should unforeseen misfortunes overtake him, then will be the time to show him the strength of your understanding, the purity of your mind, and the nature of your affection. Excite his fortitude by your example-lessen his anxiety by your vigorous resistance of calamity and diminish the pressure of misfortune by your active exertions. This will be the season for more particularly displaying the moral graces of justice, prudence, temperance, and fortitude. As mothers, remember you once were young. Let your experience and mature judgment direct and admonish your children; but let your admonitions, restraints, and direc tions, be softened by maternal affection."

"In society, be unassuming, obliging, charitable; let your benevo lence be as conspicuous in judging of conduct, as in bestowing the gifts of abundance. Cultivate a cheerful disposition, and impart its emanations; but let your gaiety be tempered by sedate thought and reflection. Be not anxious about the domestic affairs of others: curiosity is trifling and impertinent, unless excited by the laudable motive of contributing, by our counsel or assistance, to the comfort and happiness of our fellow-creatures, Avoid gossiping or talking of other people's affairs; for this practice bespeaks a weak and vacant mind, and derogates from the modesty, delicacy, and refinement of the female character."

All this advice is, no doubt, excellent; but we were no less surrized than grieved to find that, in a moral exhortation to young dies, chastity was not placed first among the virtues; and that mosty, although it only relates to external manners, occurs no more han once. We have seen a family, lately emerged from the bondage Popish superstitions, produce, under the name of one of its female branches, a modern system of education, in which religion ormed no part; and now, by this unfortunate omission, our author mishes her interesting course of natural philosophy, which every where bounds in the most pious, religious, and moral sentiments, with an nimated display of the female virtues, in which chastity has not a place. From the subsequent and concluding advice, in this otherwise most meritorious and enlightened address, of "making religious principles and PRACTICE the indispensable qualifications of both a friend and a husband," we are persuaded the author will regret this oversight still more than we. As she has often enlivened these Lectures by some very appropriate quotations from the English poets, let us advise her to cancel the last page of her "Concluding Address,' and add to it some of the admirable verses in Milton's Comus-verses, which from their exquisite elegance, taste, and true moral sentiments, are peculiarly adapted to the noble purpose of her splendid and pleasing work.

It will appear, from the copious extracts we have given, that the knowledge and principles displayed in these Lectures, are such as will command respect; and that they are every way worthy of the attention of Her Royal Highness the Princess Charlotte of Wales, to whom, by permission of her guardians, they are respectfully dedicated. We shall only add, that the numerous experiments in the different sciences here discussed, are familiarly elucidated by 36 very well executed plates, many of them from designs by Miss S. M. Bryan, we apprehend a daughter of the author.

Sophia St. Clare. A Novel. In 2 vols. 12mo. PP. 404. John

son. 1806.

THE productions of imagination are pleasant to the studious mind, as furnishing relief from the severity of science. We are acquainted with literary men, who, at the intervals of labour, seek no other mental refreshment than such as may be found in the walks of literature; and a poem, or a picture, hath often aided, by its enlivening influence, the arduous pursuits of philosophy. Of all others, the critic is, perhaps, most usefully entertained by the sports of a poetic fancy. Furrowed by thought, or frowning over dullness, his brow is relaxed into smiles by an occasional converse with the Muses; and he returns, with new pleasure, to his abstruser speculations.

That novels are to be classed high among works of invention, and

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that