so dangerous, that he had the boat fitted with my gear instead.

As to the Pomona, the chief officer of that ship, having had his attention drawn to the assertion that the process of unreaving the rope from the roller had to be performed by "hard manual exertion," repeats his former statement, that "he did the whole work himself, unassisted, and that the pendants unrove freely from the roller of their own accord; that there was no way on the ship, but the drop of the wave cleared the boat;" and he stood by his letter in all points. As this is one of the positions that my opponents have always asserted my invention would be useless in, and as it is a striking proof to the contrary, I am not at all surprised that exception was tried to be made to its working as successfully as it did. Had "Palman qui Meruit Ferat" been one of the eighteen saved, or even been present and seen what he writes about, he might have had a different opinion of the matter, as the chief officer had. But what credit, I would ask, should be attached to assertions generally, when so recklessly and unjustly made? With respect to the Austria, your correspondent states another untruth, when he says, "all Clifford's boats were swamped." I made careful personal inquiries amongst the crew immediately after their arrival in England, and found she carried eight boats, four being Francis' Life Boats, one of these on each quarter having been fitted with my gear. All four boats on the starboard side were burnt before any one could get to them, three boats on the port side were swamped, and one iron boat only reached the water in safety. I feel perfectly certain that this, the only boat saved, was fitted with my gear, but as I could not obtain any official confirmation, I have never before mentioned the circumstance.

The statement "that the numerous accidents are carefully concealed from the press" is, "Palman qui Meruit Ferat" well knows, also to be perfectly at variance with truth, and I defy him to name one single instance of such a thing having ever been attempted; but I cannot refrain from stating the course that was adopted by a leading journal, ever ready to sound the praises of the "slip-hooks." In a case of collision at night, in which the ship run into by one of Her Majesty's ships was sunk entirely ten minutes after she was struck; the quarter cutters fitted with my gear were instantly lowered by it, and all the crew saved. Yet credit was taken for its being done by Captain Kynaston's, and on my remonstrating on the injustice of such a representation, and asking for a denial of the statement, I received intimation that no such notice could be inserted, unless paid for as an advertisement.

Again; the Trafalgar is quoted as demonstrating the value of the slip-hooks, when from this very ship, in one of the heaviest gales that ever blew on the coast, a man was saved by a boat lowered by my gear.

Of the Exmouth also: Her present captain when in the Racoon, gave me what he himself termed one of the most remarkable instances he had ever known of a man being saved. This was again by my gear. His version was this: When steaming in the wake of the Princess Hohenzolin up the Tagus, the ship manning yards and firing salutes, enveloped in smoke, and steaming at full speed, one of the men fell from the yards, but the first lieutenant called two or three of the men on deck at the time, to jump into the boat, which, thus short-handed, was instantly lowered, (I use his own words), "almost on the man's head," and the man saved, although stunned by his fall.

As to the Mars, I have just seen a letter from an officer on board, who inadvertently mentions that one man had fallen overboard and been drowned, and two others also, who had been overboard, were secured by rope's ends thrown to them; but not a word about a boat being quickly lowered, and picking either up. And so long as the falls with their 150 to 200 yards of loose rope have to be paid off at each end of a boat, before it can be got down to the water, so long quickness and safety in lowering can never be gained. Falls and tackles have long since been condemned for quickly lowering merchandise, and naval infatuation cannot perpetuate their use much longer at sea for a like purpose.

In addition to the numerous cases published, to none of which I ever gave publicity, unless officially confirmed by the captain or officer of the ship, I may add one only just sent me, dated 21st December, from H.M.S. Emerald. It is that "We had occasion to use our boat this voyage. It was just after we had taken in two reefs in the topsails, one of the men fell

GENTLEMEN,-Your correspondent J. H. suggests a hook so similar to the Kynaston Patent Hook, that I send you (above) a drawing of the latter. In this place the hooks are connected by a space, and though there are two lanyards, only one is used, that being sufficient to let go both hooks simultaneously, as it would be obviously dangerous to make the process of letting go a boat dependent on two persons. The second lanyard is merely precautionary, in the extreme possibility of the aftermost one becoming foul; but as in some 250 boats in H.M. Navy now fitted with these hooks no such accident has ever occurred, we may presume the contingency is very remote. For some reason which I do not understand, but which is a well-established fact with all who are acquainted with this plan, if the boat be lowered either end foremost, the uppermost hook gives way first, which brings the boat to an even keel ere she reaches the water. In proof of this allow me to quote from a letter already in print from the late captain of H.M.S. Euryalus.

A cutter was manned to pick up a favourite dog,

the mid and crew were in the boat when the foremost davit gave way, and of course with it the bow of the boat. The man attending the disengaging line had the presence of mind to let it go, and the boat consequently went down in the water square. Three of the crew were slightly bruised, but these were the only casualties. The proof of what may be done with the slip-hooks is there."

An officer from H.M.S. Royal Albert writes: "Owing to some carelessness the boat was lowered stern foremost, but the moment the disengaging line was let go, she fell with even keel in the water, and I have observed this is invariably the case with the slip-hooks."

This would seem sufficient, but to obviate the discomfort of uneven lowering, some such plan as the following might be adopted at a trifling cost:-The chain which passes from one davit's end to the other should be divided in the centre, and a block inserted in either end, and strapped firmly together. The falls should then be passed through these blocks, One brought together and belayed to one cleat. man on board could then lower a boat with perfect ease on even keel. I am, Gentlemen, Your most obedient servant,

INDIA-RUBBER. GENTLEMEN,-The public cannot do less than highly commend you for the important and interesting articles upon india - rubber which appeared in your valuable journal on the 22nd and 29th ult.

Will you favour us with a small portion of your space for a few remarks with reference to a portion of that article of the 29th ult., as to the use of pure india-rubber as an insulator for telegraph conductors. It is there stated that Messrs. Silver and Co. were supposed to be the parties who originally advocated the use of "pure india-rubber" as an insulating medium. We beg most emphatically to deny this, and are prepared to prove that we were the original promoters of this method of insulation; we having the authority in stating that no electrician or telegraphic engineer had ever seen a conductor insulated with "pure india-rubber," as imported, prior to our patent of 1858 for the construction of telegraph cores, &c. If additional proof were necessary, we might refer you to your article in the MECHANICS' MAGAZINE of May 6th, 1859, p. 295-6. We beg also to state that we covered the first" specimen of fine No. 26 copper wire for Professor Wheatstone's telegraph, similar to that now suspended across Finsbury Circus. Our object, therefore, is simply to correct an erroneous impression that Messrs. Silver were the originators and only parties who insulated conductors with "virgin" or manufactured rubber; and we doubt not you will do us the justice to contradict a misrepresentation which you and others have inadvertently made; and sure we are that neither Messrs. Silver, nor any other honourable firm, would for one moment wilfully appear in borrowed plumes.

Your obedient servants, HALL & WELLS. Mansfield-street, Southwark, 2nd Jan., 1861.

P.S.-We beg to hand you a specimen of fine No. 26 copper wire (insulated), as used by Professor Wheatstone, showing you to what perfection wire can be insulated with india-rubber. These specimens have no tendency to decompose in the manner stated in your article, because they are not prepared by the process as adopted by other manufacturers. We warrant conductors manufactured in this way to stand the action of the atmosphere, also sea water, and never to decompose under the influence of either.

[The specimen sent with this letter is an exceedingly beautiful one. We should be sorry to imply, by any remark of ours, that Messrs. Hall & Wells were not very early and very successful in applying pure indiarubber to insulating purposes.-EDS. M. M.]

THE REVIEWS OF PHILOSOPHICAL
WORKS.

GENTLEMEN,-It cannot be considered by any right-minded and competent individual, without both surprise and indignation, that authors of all descriptions are the only persons who are incapacitated from receiving compensation for libel. Men of business can proceed against those who slander them, but no author has any power against the multitude of pseudocritics who are now emphatically the pest of every species of literature, misrepresenting both favourably and unfavourably, praising performances which deserve it not, and frequently abusing those productions which they do not understand, as well as those they do, to a greater or less extent, appreciate.

Philosophical works being the least understood and

delighted in, are the most subjected to this species of abuse. It should be remembered that all libel is falsehood in some particular, and that, whether this is wilful, or the effect of ignorance, damage to the person concerned is the result. The generality of imperfect notices of philosophical works, and all other writings, which, by an extraordinary and prodigious misnomer, are termed "reviews," contain absolute falsehoods, and this necessarily, inasmuch as general conclusions made by inconsistent individuals are never correct, except by chance. I do not refer to questions of opinion, concerning which it is hard to find two so-called critics who agree in many particulars, but to matters which the present state of science enables us to decide upon. I regret to find that the notices of philosophical works in our strictly religious magazines are, perhaps without one exception, almost as defective as they can be, and have often been annoyed at the mixture of imperfect reasoning and offensive dogmatism which composes them. It is very ridiculous in an author to consult these and similar authorities, with a view to obtaining correct accounts of his production, and when this is the case, either no notice should be taken of the work, or it should be placed in competent hands. But, unfortunately, many persons have a propensity to interfere with what they do

not understand."

SUBMARINE TELEGRAPHY. GENTLEMEN,-It is an indisputable fact that if submarine telegraphic communication were thoroughly established, it would be a mighty lever for the advancement of European enterprise and civilisation. Having read of the disastrous failure of the Rangoon, Red Sea, and other telegraph cables, I am induced to offer the following remarks in reference to this important subject.

I must say, as far as my experience goes, that some of the gentlemen employed prove to be totally incompetent for the task of accomplishing the great desideratum of the age-viz., submarine telegraphy. They have exhibited sufficient judgment only to enable them to construct cables that are absolutely useless for the localities for which they were intended. Now the core being the principal part of the cable, the question of greatest moment is what material, as an insulator, should be used in order to render the insulation perfect, at a temperature of 100° Fah

renheit ?

Some of our engineers assert (in spite of indubitable proof to the contrary) that gutta-percha, or the inferior compound known as Chatterton's compound, is most suitable for telegraph cables. Why these gentlemen still adhere to this mode of insulation (coupled with the defective spiral wire covering) is most extraordinary, knowing as they do, at the same time, that "pure india-rubber" used as an insulator, would withstand a temperature far exceeding that which is now destroying the Rangoon cable.

The monopoly, too, which exists in the manufacture of telegraph cores and cables is no mystery to those conversant with the subject; but doubtless when the reports of the Government experiments on submarine telegraphy is laid before the public, this monopoly will be done away with; until then we may expect failure in every cable that is laid.

Permit me to say, however, that I attribute the heating of the Rangoon cable to the oil and grease incorporated with the hemp in the process of manu.

THE ELASTIC PROPERTY OF THE AIR. GENTLEMEN,-As the digits employed in common arithmetic exercise a powerful influence in confining the reasoning faculties more closely to the truth than words alone in solving a problem, by their aid-and also if your correspondent, Mr. Cheverton, will carefully observe the action of winged animals during their flight-I will endeavour to convince him that the manifestation of the elasticity of the air is real in a practical sense, and not in the least degree imaginary, by the following observations.

In my former communication to your valuable journal, p. 380, I stated that the air has been found to rush into a vacant space at a velocity of about 1,300 or 1,400 ft. per second, under the atmospheric pressure, and also that if a volume of air were compressed into half its original space, and then permitted to rush out into the atmosphere, it is but reasonable to expect (because the pressure would be equal in either case) that it would do so at an equal, certainly not greater velocity than that at which it would rush into vacuum, because the friction among the particles of its own body must be definitely greater when resisted in the atmosphere, than when unresisted

in vacuo.

=

upon the propelling surfaces. But if it is altogether imaginary, and we cannot obtain more resisting power by such reaction than from that afforded by the weight of air, then we require in the first example 84 strokes instead of 3, or 2-8 times the velocity; and in the second example we require 9 strokes instead of 36, or 2.5 times the velocity, to produce the same results; and this simple law appears to hold equally true in all cases, i.e., the elasticity of the air affords nearly three times the resistance to the propelling surface, than that obtained from the weight of the air, although increased as the square of the velocity of displacement. A propelling surface of 33 square feet, for example, compressing the air a 50th part of its original volume, will obtain a resisting force equal to 33 × 41.76 1,378 lbs., and to compress the air to this extent will require a velocity equal to the 50th part of 1,200 feet, which is 24 feet per second. But the weight of the air displaced by this surface, i.e., 33 square feet, and 3 feet in depth, equal to 99 cubic feet, propelled through a distance equal to 3rd of 24 feet 8 feet, and amounting to 7.6 lbs., becomes 7.6 x 8 x8 = 486-4 lbs., being 2 times less resistance than that obtained from the elasticity of the air (1378 ÷ 486 = 2.8).

I leave it, therefore, to your numerous readers to decide whether they can conscientiously assert, maintain, or believe, that the Creator causes the elasticity of the air to remain inert--a perfect nullity-in one of its most extensive requirements, and thereby causing every bird to perform 9 strokes where 3 would equally suffice; or, in short, whether they can admit that flying animals are condemned to labour with three or four times the exertion in order to support themselves in the air, than they would find necessary if freely permitted to avail themselves of the value of its elasticity? Although Nature so modestly conceals the operation of her laws from us, yet I again aver that the elastic property of the air is the primary and fundamental principle of air navigation, and on this property all flying animals depend for support during their flight. It is the elastic property of the air when properly developed which does and will constitute the resistance to all physical or mechanical forces, and enable them to derive from the air a proing it. It is also this property of the air (which has pelling force equal to the power employed in develop. of all flying creatures with the same comparative so long been neglected by us) that sustains the bodies ease, and with so little effort on their part, that they can as easily rise up into the aërial fluid as fishes can regard of this property by us that all our former in the watery fluid; and it is owing to the total disattempts to navigate the air have been rendered abortive.

I am, Gentlemen, your most obedient servant, W. QUARTERMAIN. 41 London-wall.

DUCE THE POPULAR INDIFFERENCE TO SCIENCE.

If then we take 1350 ft. per second as the unit of the atmospheric velocity into vacuum, and reduce such velocity 10 per cent. for the retardation arising from friction when resisted by the atmosphere, we have 1350-135, equal to, say, 1200 ft. per second. Now if 14 lbs. per square inch, and the unit of its velocity in we take the unit of the atmospheric pressure at then furnished with data as a basis for our calculations air at 1200 ft. per second, under such pressure, we are equally as reliable as that afforded us by our knowledge of the density and velocity of water. above) will then stand thus: a bird possessing a surThe illustration given at p. 381 (corrected as face of wing equal to 180 square inches, by raising and depressing such surface through a distance of 96 in. three times per second, must impart to the air a force equal to ō-22 lbs., because such force and velocity will compress such a column of air a 500th part of its original volume, and consequently develope a reaction from its elastic property equal to 180 x 14 ON SOME OF THE CAUSES WHICH PRO= 2,160 lbs., which divided by 500 shows 5.22 lbs. And as the velocity of the air is proportional to its rate of compression, by compressing it a 500th part of its original volume, the bird will impart to it a velocity equal to the 500th part of 1200 ft. per second, which is 24 ft. per sec., or 9.6 inches per stroke. Now if this is imaginary, and the bird can only obtain from the air a reaction equal to that of the weight of air displaced, then we have 180 x 96 = 1728 cubic inches of air displaced at each stroke, and which at 31 grains per 100 cubic inches amount to 535-7 grains, and this weight displaced three times per second increased as the square of the velocity of displacement, becomes 3 x 3 x 535'7 = 4,912 grains, and this to equal 522 lbs. will require 8.25 strokes per second; being 8.25 x 8.25 x 5357 = 36,460 grains, or 5-21 lbs. Again, suppose we take a bird weighing one pound, having a surface of wing equal to 72 square inches, and that it raises and depresses them through a distance of five inches at each stroke nine times per sec., the weight of air displaced in this case will be equal to 72 x 5 × 31 ÷ 100 = 112 grains at each stroke, and, increased as above, becomes 9 x 9 x 1129,072 grains, or 1.3 lbs. But if in this case the bird compresses such column of air a 800th part of its original volume, we have 72 × 144 = 1,044 lbs., which divided by 800 shows 13 lbs. resisting force. To compress such column of air to the extent will require a velocity equal to the 800th part of 1200 ft., or 1.5 ft. per second, and the surface being propelled through a distance of five inches at each stroke, shows 36 strokes per second, as the velocity required.

In these two examples, then, if the manifestation of the elasticity of the air is real, we find in the first example a velocity of 24 ft. or three strokes per second is sufficient to develope a reaction equal to 5 lbs., and in the second example a velocity of 1.5 ft., or 34 strokes per second, will develop a reaction of 1-3 lbs.

GENTLEMEN,-Notwithstanding Mechanics' Institutions, and the apparatus connected therewith, there is still popularly a very great amount of indifference concerning science and scientific advancement; and this it would be a great work to overcome. The principal causes which produce this unfortunate result are two; first, the want of scientific instruction in public and other schools, which would in many cases result in the formation of a scientific habit; and secondly, the want of museums and scientific lectures. I do not hesitate to affirm that the, in many cases, total want of scientific instruction in public and other schools, is a disgrace both to the country and the age of the world in which we live. The undue partiality for classical studies, in many cases to the detriment of pure mathematics, which schoolmasters as a rule evince, is simply a delusion, and therefore every person who knows this should use what influence he possesses, in order that modern science should receive from the young, and indeed individuals of every age, the attention which it deserves. A correspondent has, in No 5 of The Provincial Magazine, shown that the results of scientific study are far more important than are the various refinements occasionally struck out in connection with the dead languages. The facts alluded to are perfectly unanswerable, and the communication is one to which reference may satisfactorily be made.

Museums are very important means for the diffusion of scientific knowledge, and one should therefore be established wherever this is possible, which is the case at any rate in every town. A scientific museum is not a heterogeneous collection of materials, which is sometimes dignified by this name, but an assemblage of objects which are at any rate of some utility in a

so dangerous, that he had the boat fitted with my gear instead.

As to the Pomona, the chief officer of that ship, having had his attention drawn to the assertion that the process of unreaving the rope from the roller had to be performed by "hard manual exertion," repeats his former statement, that "he did the whole work himself, unassisted, and that the pendants unrove freely from the roller of their own accord; that there was

66

no way on the ship, but the drop of the wave cleared the boat;" and he stood by his letter in all points. As this is one of the positions that my opponents have always asserted my invention would be useless in, and as it is a striking proof to the contrary, I am not at all surprised that exception was tried to be made to its working as successfully as it did. Had Palman qui Meruit Ferat" been one of the eighteen saved, or even been present and seen what he writes about, he might have had a different opinion of the matter, as the chief officer had. But what credit, I would ask, should be attached to assertions generally, when so recklessly and unjustly made? With respect to the Austria, your correspondent states another untruth, when he says, "all Clifford's boats were swamped." I made careful personal inquiries amongst the crew immediately after their arrival in England, and found she carried eight boats, four being Francis' Life Boats, one of these on each quarter having been fitted with my gear. All four boats on the starboard side were burnt before any one could get to them, three boats on the port side were swamped, and one iron boat only reached the water in safety. I feel perfectly certain that this, the only boat saved, was fitted with my gear, but as I could not obtain any official confirmation, I have never before mentioned

the circumstance.

The statement "that the numerous accidents are carefully concealed from the press" is, "Palman qui Meruit Ferat" well knows, also to be perfectly at variance with truth, and I defy him to name one single instance of such a thing having ever been attempted; but I cannot refrain from stating the course that was adopted by a leading journal, ever ready to sound the praises of the "slip-hooks." In a case of collision at night, in which the ship run into by one of Her Majesty's ships was sunk entirely ten minutes after she was struck; the quarter cutters fitted with my gear were instantly lowered by it, and all the crew saved. Yet credit was taken for its being done by Captain Kynaston's, and on my remonstrating on the injustice of such a representation, and asking for a denial of the statement, I received intimation that no such notice could be inserted, unless paid for as an advertisement.

Again; the Trafalgar is quoted as demonstrating the value of the slip-hooks, when from this very ship, in one of the heaviest gales that ever blew on the coast, a man was saved by a boat lowered by my gear.

Of the Exmouth also: Her present captain when in the Racoon, gave me what he himself termed one of the most remarkable instances he had ever known of a man being saved. This was again by my gear. His version was this: When steaming in the wake of the Princess Hohenzolin up the Tagus, the ship manning yards and firing salutes, enveloped in smoke, and steaming at full speed, one of the men fell from the yards, but the first lieutenant called two or three of the men on deck at the time, to jump into the boat, which, thus short-handed, was instantly lowered, (I use his own words), "almost on the man's head," and the man saved, although stunned by his fall.

As to the Mars, I have just seen a letter from an officer on board, who inadvertently mentions that one man had fallen overboard and been drowned, and two others also, who had been overboard, were secured by rope's ends thrown to them; but not a word about a boat being quickly lowered, and picking either up. And so long as the falls with their 150 to 200 yards of loose rope have to be paid off at each end of a boat, before it can be got down to the water, so long quickness and safety in lowering can never be gained. Falls and tackles have long since been condemned for quickly lowering merchandise, and naval infatuation cannot perpetuate their use much longer at sea for a like purpose.

In addition to the numerous cases published, to none of which I ever gave publicity, unless officially confirmed by the captain or officer of the ship, I may add one only just sent me, dated 21st December, from H.M.S. Emerald. It is that "We had occasion to use our boat this voyage. It was just after we had taken in two reefs in the topsails, one of the men fell

off the jib-boom-blowing hard at the time-but in less than ten minutes the man was picked up."

As to the authority to be attached to every case of lives saved, I may remind you, that in nearly all ships where it has been employed in the merchant service, its use has been made compulsory by the Government, and consequently their reports have not come to me from any very friendly source.

lower a boat against any other system or invention; I now once more repeat my former challenge to I, to have one man only, the others, any number they like, and under any conditions of speed, weather, or position; and I am quite ready to bear any portion of the expense consequent on such trials, if under such regulations as you name-viz., "before the various officers of the different departments of the Government taking special supervision of such matters."

In conclusion, I have always scrupulously avoided comment on any other man's invention, and only say what I ever do in self-defence, and in reply to the unjust attacks made on my system anonymously. I have never in any public document advanced the pretensions of my invention before any other as entitling it to the special consideration of the Government, beyond what it was fully able to prove it deserved; and I must thank you, Gentlemen, most sincerely for giving me credit for having taken this course, the only one I feel to be honourable. Nay, I have used with the Admiralty and every department of the Government, long since, the very arguments you advanced in your article that all inventors were entitled to like consideration. The public interest and the good of humanity demands it should be so; and the open and manly feeling of fair play that one looks for in so honourable a profession as the navy, should make a British officer scorn any other road to distinction and preferment, much less assert under a false name what he dares not acknowledge under his own. CHARLES CLIFFORD.

h

GENTLEMEN,-Your correspondent J. H. suggests send you (above) a drawing of the latter. In this place a hook so similar to the Kynaston Patent Hook, that I the hooks are connected by a space, and though there are two lanyards, only one is used, that being sufficient to let go both hooks simultaneously, as it would be obviously dangerous to make the process of letting go a boat dependent on two persons. The second lanyard is merely precautionary, in the extreme possibility of the aftermost one becoming foul; but as in some 250 boats in H.M. Navy now fitted with these hooks no such accident has ever occurred, we may presume the contingency is very remote. For some reason which I do not understand, but which is a well-established fact with all who are acquainted with this plan, if the boat be lowered either end foremost, the uppermost hook gives way first, which brings the boat to an even keel ere she reaches the water. In proof of this allow me to quote from a letter already in print from the late captain of H.M.S. Euryalus.

A cutter was manned to pick up a favourite dog,

the mid and crew were in the boat when the foremost davit gave way, and of course with it the bow of the boat. The man attending the disengaging line had the presence of mind to let it go, and the boat consequently went down in the water square. Three of the crew were slightly bruised, but these were the only casualties. The proof of what may be done with the slip-hooks is there."

An officer from H.M.S. Royal Albert writes: "Owing most, but the moment the disengaging line was let go, to some carelessness the boat was lowered stern foreshe fell with even keel in the water, and I have observed this is invariably the case with the slip-hooks." This would seem sufficient, but to obviate the discomfort of uneven lowering, some such plan as the following might be adopted at a trifling cost:-The chain which passes from one davit's end to the other should be divided in the centre, and a block inserted in either end, and strapped firmly together. The falls should then be passed through these blocks, brought together and belayed to one cleat. man on board could then lower a boat with perfect ease on even keel. I am, Gentlemen, Your most obedient servant,

INDIA-RUBBER.

One

C. M.

GENTLEMEN, highly commend you for the important and interestThe public cannot do less than ing articles upon india - rubber which appeared in your valuable journal on the 22nd and 29th ult.

Will you favour us with a small portion of your that article of the 29th ult., as to the use of pure space for a few remarks with reference to a portion of india-rubber as an insulator for telegraph conductors. It is there stated that Messrs. Silver and Co. were supposed to be the parties who originally advocated the use of "pure india-rubber" as an insulating medium. We beg most emphatically to deny this, and are prepared to prove that we were the original promoters of this method of insulation; we having the authority in stating that no electrician or telegraphic engineer had ever seen a conductor insulated with "pure india-rubber," as imported, prior to our patent of 1858 for the construction of telegraph cores, &c. If additional proof were necessary, we might refer you to your article in the MECHANICS' MAGAZINE of May 6th, 1859, p. 295-6. We beg also to state that we covered the "first" specimen of fine No. 26 copper wire for Professor Wheatstone's telegraph, similar to that now suspended across Finsbury Circus. Our object, therefore, is simply to correct an erroneous impression that Messrs. Silver were the originators and only parties who insulated conductors with "virgin" or manufactured rubber; and we doubt not you will do us the justice to contradict a misrepresentation which you and others have inadvertently made; and sure we are that neither Messrs. Silver, nor any other honourable firm, would for one moment wilfully appear in borrowed plumes.

Your obedient servants, HALL & WELLS. Mansfield-street, Southwark, 2nd Jan., 1861. P.S.-We beg to hand you a specimen of fine No. 26 copper wire (insulated), as used by Professor Wheatstone, showing you to what perfection wire can be insulated with india-rubber. These specimens have no tendency to decompose in the manner stated in your article, because they are not prepared by the process as adopted by other manufacturers. We warrant conductors manufactured in this way to stand the action of the atmosphere, also sea water, and never to decompose under the influence of either.

H. & W.

[The specimen sent with this letter is an exceedingly beautiful one. We should be sorry to imply, by any remark of ours, that Messrs. Hall & Wells were not rubber to insulating purposes.—EDS. M. M.] very early and very successful in applying pure india

THE REVIEWS OF PHILOSOPHICAL
WORKS.

right-minded and competent individual, without both GENTLEMEN,It cannot be considered by any surprise and indignation, that authors of all descriptions are the only persons who are incapacitated from receiving compensation for libel. Men of business can proceed against those who slander them, but no critics who are now emphatically the pest of every author has any power against the multitude of pseudospecies of literature, misrepresenting both favourably and unfavourably, praising performances which dewhich they do not understand, as well as those they serve it not, and frequently abusing those productions do, to a greater or less extent, appreciate. Philosophical works being the least understood and

The statement "that the numerous accidents are carefully concealed from the press" is, "Palman qui Meruit Ferat" well knows, also to be perfectly at variance with truth, and I defy him to name one single instance of such a thing having ever been attempted; but I cannot refrain from stating the course that was adopted by a leading journal, ever ready to sound the praises of the slip-hooks." In a case of collision at night, in which the ship run into by one of Her Majesty's ships was sunk entirely ten minutes after she was struck; the quarter cutters fitted with my gear were instantly lowered by it, and all the crew saved. Yet credit was taken for its being done by Captain Kynaston's, and on my remonstrating on the injustice of such a representation, and asking for a denial of the statement, I received intimation that no such notice could be inserted, unless paid for as an advertisement.

Again; the Trafalgar is quoted as demonstrating the value of the slip-hooks, when from this very ship, in one of the heaviest gales that ever blew on the coast, a man was saved by a boat lowered by my gear.

Of the Exmouth also: Her present captain when in the Racoon, gave me what he himself termed one of the most remarkable instances he had ever known of a man being saved. This was again by my gear. His version was this: When steaming in the wake of the Princess Hohenzolin up the Tagus, the ship manning yards and firing salutes, enveloped in smoke, and steaming at full speed, one of the men fell from the yards, but the first lieu tenant called two or three of the men on deck at the time, to jump into the boat, which, thus short-handed, was instantly lowered, (I use his own words), "almost on the man's head," and the man saved, although stunned by his fall.

As to the Mars, I have just seen a letter from an officer on board, who inadvertently mentions that one man had fallen overboard and been drowned, and two others also, who had been overboard, were secured by rope's ends thrown to them; but not a word about a boat being quickly lowered, and picking either up. And so long as the falls with their 150 to 200 yards of loose rope have to be paid off at each end of a boat, before it can be got down to the water, so long quickness and safety in lowering can never be gained. Falls and tackles have long since been condemned for quickly lowering merchandise, and naval infatuation cannot perpetuate their use much longer at sea for a like purpose.

In addition to the numerous cases published, to none of which I ever gave publicity, unless officially confirmed by the captain or officer of the ship, I may add one only just sent me, dated 21st December, from H.M.S. Emerald. It is that "We had occasion to use our boat this voyage. It was just after we had taken in two reefs in the topsails, one of the men fell

the mid and crew were in the boat when the foremost davit gave way, and of course with it the bow of the boat. The man attending the disengaging line had the presence of mind to let it go, and the boat consequently went down in the water square. Three of the crew were slightly bruised, but these were the only casualties. The proof of what may be done with the slip-hooks is there."

An officer from H.M.S. Royal Albert writes: "Owing to some carelessness the boat was lowered stern foremost, but the moment the disengaging line was let go, she fell with even keel in the water, and I have observed this is invariably the case with the slip-hooks." This would seem sufficient, but to obviate the discomfort of uneven lowering, some such plan as the following might be adopted at a trifling cost:-The chain which passes from one davit's end to the other should be divided in the centre, and a block inserted in either end, and strapped firmly together. The falls should then be passed through these blocks, brought together and belayed to one cleat. One man on board could then lower a boat with perfect ease on even keel. I am, Gentlemen, Your most obedient servant,

THE REVIEWS OF PHILOSOPHICAL
WORKS.

right-minded and competent individual, without both GENTLEMEN,-It cannot be considered by any surprise and indignation, that authors of all descriptions are the only persons who are incapacitated from receiving compensation for libel. Men of business can proceed against those who slander them, but no author has any power against the multitude of pseudocritics who are now emphatically the pest of every species of literature, misrepresenting both favourably and unfavourably, praising performances which deserve it not, and frequently abusing those productions which they do not understand, as well as those they do, to a greater or less extent, appreciate.

Philosophical works being the least understood and