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able circuit of different conductors, perfectly continuous, and will communicate a fenfible fhock.
Mr. Walsh terminates the curious account of his experiments by the following fpirited and appropriate address to Dr. Franklin: I rejoice, fays he, in addreffing thefe communications to you. He, who predicted and fhewed that electricity wings the formidable bolt of the atmosphere, will hear with attention, that in the deep it fpeeds an humbler bolt, filent and invifible. He, who analyfed the electrified phial, will hear with pleasure that its laws prevail in animate phials: He, who by reafon became an electrician, will hear with reverence of an instinctive electrician, gifted in his birth with a wonderful apparatus, and with the skill to use it.'
Though we have extended this article to fo confiderable a length, we cannot omit an interefting anatomical obfervation made by Mr. Hunter. In his diffection of the electric organs of the torpedo, he obferved an uncommonly liberal diftribution of nerves to these parts; ramifying in every direction between the columns, and fending in fmall branches upon each of the numerous partitions into which every one of them is divided. Now nerves are given to parts either for the purposes of fenfation, or action: but the extraordinary number and magnitude of these nerves, which do not feem neceffary for any fenfation that can be fuppofed to belong to the electric organs and which cannot be thought fubfervient to mufcular action, as they exceed the proportion allowed to the most active animals ; induce the Author to conclude that they are in fome manner concerned in the formation, collection, or management of the electric fluid. How far, he adds, we may hence be led to an explanation of the power and functions of the nerves in general, time and future difcoveries alone can determine. Article 35. On fome Improvements in the Elric Machine. In a Letter from Dr. Nooth to Dr. Franklin, F. R. S.
By the ufe of amalgam, and by the proper application of a piece of dry filk, or other non conducting fubftance, to the rubber of an electrical machine, practical electricians have for fome time paft been enabled to defy, in a great measure, the viciffitudes of the weather, greatly to increase the power of excitation, and to prevent the return of the electric fluid to the earth, after the globe had pumped it up from thence, by its friction against the rubber.
In this article the Author has very judicioufiy investigated the best difpofition of the conducting and non-conducting parts of the cushion or rubber. He very properly confiders the polerior part of it, or that which correfponds with the defcending part of the globe, and to which it first arrives in its revolution, as the part følely concerned in the excitation; and ob
ferves, that it ought therefore to be conftructed of the most perfectly conducting materials: or, in other words, that the amalgam fhould be applied and, as far as poffible, confined to this part of the rubber. On the other hand, the filk flap, or nonconducting fubftance, ought to be fixed at the anterior part of the rubber, and precifely at the limit or boundary where the exciting power, or the friction of the cushion, ceases; so as to prevent the return of the electric matter to it, and that it may be conveyed, by the revolution of the globe, without any di minution, to the points of the prime conductor. He appears to us however to refine too far, when he advifes that the fupport to the rubber should likewife have its conducting and nonconducting fide, by making it of baked wood, and covering the pofterior half of it with tinfoil.
The 29th and 34th articles contain accounts of the effects of two thunder-ftorms, which exhibit fome interefting phenomena. The first of them recites thofe that attended two explosions at Steeple - Afhton, and Holt, in the County of Wilts, and which prove the danger of placing any confiderable quantity of iron in the upper part of chimneys, unprovided with a conductor continued down to the earth.
In the fecond of thefe articles, Sir William Hamilton relates the curious appearances obferved in a thunder-ftorm that ftruck the house of Lord Tylney at Naples, on one of his Lordship's affembly nights, when there were near 500 perfons in it. There have been few accounts of this kind which prove more clearly the perfect identity of lightning and the electric matter, in all their operations. None of this large company were effentially hurt, though many received fmart fhocks. Their escape appears to have been in a great measure owing to the lightning's having divided itfelf, fo as to pass through nine rooms; invited to and conducted through them, partly by the bell wires, but ftil more by the gilding with which they were profufely ornamented. In feveral of the rooms it was conveyed through no lefs than eight or nine gilt bands in each, which defcended from the cornice; exhibiting marks of its paffage through all of them, by difcolouring and partly diffipating them, METEOROLOGY.
Article 38. Account of a new Hygrometer. By M. J. A. De Luc, Citizen of Geneva, F. R. S. and Correfpond. Member of the Academies of Paris and of Montpelier.
An exact and comparable hygrometer has long been a defideratum among philofophers. The nearest approach that we recollect, towards the conftruction of fuch an inftrument, was lately made by Mr. Smeaton; whofe defcription of an apparatus for this purpose, in the 61st volume of these Transactions, was noticed by us in our 48th volume, March 1773, page 225.
In the present attempt to difcover a method of measuring the moisture of the air, in as determinate a manner as we are now enabled, by means of the thermometer and barometer, to meafure its heat and gravity, the Author exhibits the same spirit of invention, and precision, that distinguish his Enquiries into the different Modifications of the Atmosphere. On his entering upon the prefent investigation, he found that the effential requifites in an inftrument intended to measure humidity, were the three following:
ift, The fettling of a fixed point, from which every measure of the fame kind fhould be taken; fuch, for inftance, as that of boiling water in a thermometer, when the barometer is at a certain height? Such a fixed point the Author at first ineffectually fought for in abfolute drynefs. The difficulties he met with at this extremity of the projected fcale obliged him foon to turn his attention to the other extreme, abfolute humidity. Here he was led to con fider water itself as the maximum or limit; for a body plunged into that fluid, and foaked so as not to receive any more, may be confidered as arrived at the degree of extreme humidity. And that heat might not produce any variation in this fixed point, M. De Luc determined that the foaking power of melting ice fhould be the bafis of his hygrometrical fcale. It was requifite however to find a substance capable of being altered in its dimenfions by the foaking power of water, without being diffolved or in other respects altered by it. In queft of fuch a substance the Author fearched the mineral, vegetable, and animal kingdoms, and at length fixed upon ivory; which he found to be a body enfily affected by the impreffions of drought and moisture.
The other two requifites in an inftrument deftined to mea fure drought and humidity are, 2dly, Degrees equally deter mined, or comparable, in different hygrometers;' as are thofe in the thermometrical fcales of Reaumur, Fahrenheit, &c.-and, 3dly, Conftancy in the variations produced by the fame differences of humidity.'
These requifites the ingenious Author appears in a great meafure to have attained, by the conftruction of a fimple and commodious inftrument; for his copious and accurate defcription of which, illuftrated with a plate, we must neceffarily refer our philofophical Readers to the article itfelf. To give a general idea of its form and manner of action, we hall only obferve that it confifts of a hollow ivory cylinder or bulb filled with mercury, with a glafs tube annexed, in the form of a thermometer; and that it indicates an increase of humidity in the air, by the fall of the mercury in the tube, in consequence of the dilatation of the ivory bulb, and the enlargement of its capacity, by means of the moiffure attracted by it. On the con trary, it indicates a dry ftate of the air, by the ascent of the
mercury, in confequence of the contraction of the bulb, on the evaporation of that moisture which had before dilated it, In the Author's inftrument, the range or extent of the fcale, from abfolute humidity to extreme drynefs, appears to be about fix inches.
It is evident that an inftrument thus conftruded is in fact a thermometer, and must neceffarily be affected by the viciffitudes of heat and cold, as well as by thofe of drynefs and moisture; or that it must act as a thermometer, as well as an hygrometer. This imperfection however is eafily corrected by means of fome ingenious and fimple expedients, employed in the original conftruction and fubfequent ufe of the inftrument; in confequence of which the variations in the temperature of the air, though they produce their full effects on the inftrument, as a thermometer, do not interfere with or embarrass its indications as an hygrometer, We have not room to explain how these purpoles are effected; but we heartily recommend to the curious the attentive perufal of the whole article, as containing an excellent Specimen of philofophical investigation, and an accurate defcription of an ufeful addition to the apparatus of a meteorological obferver.
The 27th article of this class is only the continuation of an annual regifter of the barometer, &c. kept at Lyndon in RutJand, for the year 1772.
Article 31. Experiments and Obfervations on the Singing of Birds,
This paper contains fome new and curious obfervations on the finging of birds, deduced from a large experience on this - fubject. The Author affirms that notes in birds are no more innate than language in man;' and that the fong of any parti cular bird intirely depends on the mafter under whom he has been educated, and the capability of his organs to imitate the founds which he has the most frequent opportunities of hearing.
Mr. B. has repeatedly taken linnets from the neft, and has put them under the tuition of the beft finging larks. The pupil never gave any fpecimens of the linnet's fong; but adhered entirely to that of the lark, his inftructor. When he has been thoroughly grounded, or his fong has been completely fixed, he has kept him in a room, for a quarter of a year, with two other linnets in full fong: but even this company did not stagger him in his part; he ftedfaftly perfifted in finging the notes of the lark, his mafter, without borrowing a fingle paffage from his brother linnets.
Further, we are told that a nestling linnet, educated under a foreigner, a rare bird from Africa of the finch tribe, called the vengolina, fung the notes of his African mafter fo correctly,
that it was impoffible to diftinguifh his fong from that of his foreign inftructor; nor was he ever heard to utter a fingle note by which he could have been known to be a linnet.
It is true that birds, in a wild ftate, adhere fteadily to the fong peculiar to their fpecies; but this, the Author obferves, proceeds from the neftlings attending only to the inftruction of the parent bird, while he difregards the notes of all the other birds, who may perhaps be finging round him. A common fparrow accordingly only learns from the parent bird to chirp : but when one has been taken from the neft by the Author, and has been brought up under a linnet, being at the fame time accidentally within the hearing of a goldfinch, his fong was a mixture of that of the linnet, and that of the goldfinch. A young robin educated by the Author under a nightingale, not quite a fortnight, at the end of which time the nightingale became perfectly mute, fung three parts in four of the nightingale's fong. The reft of his fong was what the bird-catchers, it feems, call rubbish, or notes of no particular character.
If it be asked how birds firft acquired the notes peculiar to each species, the Author answers that the origin of the notes in birds is as difficult to be traced, as that of language among dif ferent nations. After many curious remarks, in which Mr. B. gives the result of various experiments that he has made on this fubject, he confiders the pitch of the notes of finging birds, and how far their intervals refemble or are commenfurable with thofe in our mufic. Their pitch in general is confiderably higher than the acuteft notes in our fcale; and the intervals ufed by them are inappreciables, or too minute to be compared with the groffer intervals in our gamut. The Author however gives us feveral conjectures on thefe heads, fome of which appear to us not to be perfectly confiftent with each other; nor can we think with him, that there is no difagreeable diffonance, that is not properly refolved, attending the Dutch concert of a dozen finging birds performing in the fame room.
Whatever may be the natural musical intervals of the feathered choir, many of them, it is well known, particularly the bullfinch, can accurately execute thofe of our fcale, or according to the common phrase, fing a good fong. And as they adhere fteadily to the notes of the particular melody which they have been taught, Mr. B. propofes to turn this imitative talent to further account, by teaching two of them to perform a duet. He has here accordingly given a few fhort pieces contrived for this purpose; in which the compofer has, in the construction of the fecond treble, very properly attended to the expected indocility or unsteadinefs of his pupils, with refpect to time; and has accordingly confined the harmony of the fecond treble to the unifon and the fifth of the key.