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which he calls the Cuculus Indicator, or Honey Guide; which poffeffes the fingular power and instinct not only of discovering the wild bee-hives, but of communicating fuch discovery by a fignal or cry; not only to the Hottentots, and to the Dutch who are fettled in those interior and wild parts of the country; but likewise to a certain species of quadruped, which the Dutch name Ratel, and who it feems has a fweet tooth. In return, the honey-hunters never fail, at least the Bipedes, to leave a fmall portion for their conductor; but commonly take care not to leave so much as would fatisfy its hunger.' Accordingly, the bird's appetite being only whetted by this parfimony, it is obliged to commit a fecond treafon, by discovering another bee's neft, in hopes of a better falary. It is further obferved, that the nearer the bird approaches the hidden hive, the more frequently it repeats its call, and feems more impatient.'
In the 7th Article, the Abbé Dicquemare continues the account of his further difcoveries and obfervations on the internal organization, generation, reproduction, and other remarkable phenomena obferved in the Sea Anemonies. The fourth fpecies of this animal affords a fingularity not found in the fresh water Polypus ;-that of multiplying by fpontaneously tearing off fmall fhreds from its body.
In the 2d Article, Mr. Marfham relates fome experiments tending to prove that the annual increase of trees is promoted by washing and rubbing their stems; as Mr. Evelyn and Dr. Hales had propofed.
PAPERS relating to ELECTRICITY.
Article 6. An Account of jome new Electrical Experiments. By Mr. Tiberius Cavallo.
This Article contains the defcription and uses of the Author's Atmospherical Electrometer, and of his Electrometer for the Rain; which we have already noticed in our late account of his Treatife on Electricity: together with a few experiments made with a glass tube hermetically fealed, and having fome quickfilver contained in it.
Article 8. Experiments and Obfervations in Electricity. By William Henly, F. R. S.
This long Article, which is divided into three parts, contains, first, fome remarks on the effects of lamp black, mixed with tar or oil, as protectors of bodies coated with them, from the ftroke of lightning; together with fome experiments in artificial electricity, in which fimilar effects are produced.
In the fecond part the Author gives an account of the ftrong electricity produced in cakes of chocolate, on turning them out of the tin pans in which they had been cooled; and of the reB 2
covery of that property, when they had loft it, hy melting the chocolate afresh with a fmall quantity of olive oil.
The third part contains feveral experiments, principally made with a view to illuftrate the Franklinian theory of the Leyden vial. Among them we find the following, with an account of which the Author had furnifhed Mr. Cavallo; from whofe treatise, where it is produced to fhew the real courfe of the electric fluid in a difcharge, we tranfcribed. it, with some remarks, in our Review for November laft, page 365. We fhall here give it in the Author's own words:
In the melting fmall wires fome inches in length, I have often obferved the wire to become red-hot, firft at that end in contact with the difcharging rod; and the rednefs has proceeded gradually, and regularly, towards the coating of the jars or battery; plainly and fully demonftrating the direction of the electric matter in the discharge of the jars or battery, which, for this experiment, were always charged pofitively. This phenomenon hath alfo been obferved by Mr. Bell, and many times by Mr. Nairne.'
Thefe experiments are fucceeded by fome very fingular inftances of glafs retaining its electricity for a long time after it had been excited. In one fet of obfervations, a cylinder was excited on the 3d of February. Its ftate was generally examined from day to day, by prefenting Mr. Canton's balls to it; and its electrical power was estimated by the distance at which it would caufe thefe balls to feparate. After fo long an interval as five weeks, viz. on the 10th of March following, (when an end was put to the experiment) the cylinder retained fo much of its electricity, as to caufe the balls to diverge at the diftance of eight inches from it. The variations in the apparent electricity of the cylinder, and its total difappearance, and reappearance, feveral times during this long interval, are very extraordinary. We shall select an inftance or two from the Author's regifter.
So far back as February 14, at ten at night, the cylinder fhewed no figns of electricity, nor at the hours of feven, eight, and ten of March 9 (the day preceding the laft obfervation abovementioned ;) and yet on this last-mentioned day, at eight in the forenoon, it made the balls to separate at the diftance of nine inches from it. In a former fet of obfervations, the electric power in the cylinder was often made to difappear by breathing upon it; or was apparently deftroyed by applying fame round it: nevertheless, not long after thefe operations we fometimes find the balls feparating at greater diftances than before. The caufe of thefe curious phenomena, Mr. Henly obferves, is, no doubt, the excited electricity lodged in the
pores of the glass, acting upon the vapour in the air of the room.'
In a poftfcript, Mr. Henly adds the refults of a very great number of experiments, made with mineral, vegetable, animal, and artificial fubftances, fixed or tied upon the end of a stick of fealing wax, and excited by friction against a woollen garment, or a piece of foft black filk; in order to determine the kind, and degree of ftrength, of the electricity produced in these subftances refpectively.
PAPERS relating to METEOROLOGY.
Article 13. Obfervations on the annual Evaporation at Liverpoo in Lancashire; and on Evaporation confidered as a Teft of the Moisture or Dryness of the Atmosphere. By Dr. Dobfon of Liverpool.
This Article contains the refults of four years obfervations, of the quantity of water evaporated monthly in a cylindrical veffel; and of the quantity of rain that fell into another veffel of the fame diameter; accompanied with correfpondent obfervations of the temperature of the air, and the force of the wind. They appear to have been made with great accuracy, and with a particular attention to fuch circumftances as might influence or difturb the refults. Though we cannot particularize many of the obfervations, we fhall give a general account of them, and of the inferences which the Author juftly, in our opinion, deduces from them.
They tend, in the first place, to give us a clearer and juster idea than has generally been entertained, with refpect to the moisture and drynefs of the air; and to fhew that these are not to be estimated from the greater or finaller quantity of rain that has fallen in any place, or during any particular feafon; but that evaporation is the more proper and accurate teft of the moift or dry state of the atmosphere. This doctrine is founded on thefe propofitions ;—that air is an active folvent of water; and that its power, as a menftruum, is increafed in proportion to its drynefs, as well as to its heat, and agitation. The degree of evaporation, therefore, or the quantity of water taken away from the surface of a mafs of that fluid, by the air, in a given time and place, feems to be the true index or criterion of the drynefs of the air, during the time of the procefs; regard being, at the fame time, had to the temperature of the fealon, and winds.
For example, the depth of rain, or the quantity which fell, in the last three months of the year 1773, was more than double its depth in the first three months of that year: yet the air in the first mentioned period was not moister than in the latter; for the evaporation was found to be nearly equal in both these
feafons; and the temperature of the air, and the ftate of the winds were nearly the fame in both the periods.
Again, the rain in the year 1775 greatly exceeded that in 1774; but the air muft have been drier in the first of these seafons for it was found by observation that, notwithstanding this larger fall of rain in 1775, the evaporation from the cylindrical veffel had been greater. In other words, the drynefs of the air, or its power of diffolving water, was greater in the year in which there was the greateft quantity of rain. Accordingly, without any appearance of rain, the air may be damp; and, notwithstanding heavy rains, it may be dry.
The Author terminates this paper by a very proper diftinction of the three different ftates in which water exifts, with refpect to air. These are, ift, That of perfect folution; in which cafe the air is not only clear and heavy, but likewife dry; because its power of folution remains ftill active, and it is not difpofed tot part with the water with which it is combined; as is the cafe in long continued fummer droughts. 2dly, In a ftate of beginning precipitation; in which cafe the folvent power of the air is diminished, and it becomes moift and foggy. Or, 3dly, completely precipitated, and falling in drops of rain. These three ftates, we fcarce need to add, are perfectly analogous to the common chemical proceffes of folution, mixture, and pre cipitation.
Articles 17, 18, and 19, contain the meteorological registers communicated to the Society, as ufual, by Thomas Barker, Efq; at Lyndon, and Dr. Samuel Farr, at Bristol; and the Society's own Journal for the year 1776. The mean of the variation, obferved in June and July was 21 degrees and 47 minutes W. and the mean of the obfervations made with the dipping needle, 72 degrees and 30 minutes.
ASTRONOMICAL and MATHEMATICAL PAPERS.
Article 9. Contains an account of the tides in the Adriatic, by the Abbé Tealdo; including the daily obfervations of Signor Temanza; which tend greatly to illuftrate and confirm the Newtonian theory on that fubject.
In the 10th Article, Mr. Peter Wargentin, F. R. S. and Secretary to the Royal Academy of Sciences at Stockholm, com municates to Mr Mafkelyne feveral observations tending to af certain, with more precifion than has hitherto been attained,
the difference of longitude of the Royal Obfervatories of Paris and Greenwich, refulting from the eclipfes of Jupiter's first fatellite, obferved during the laft ten years.'-This ancient and experienced aftronomer, however, does not appear to entertain fo good an opinion of the accuracy of this method of determining the longitude of places, as of that which depends on the ob
ferving the occultations of fixed ftars by the moon. He adds, nevertheless, a table, containing four or five hundred immerfions and emerfions of Jupiter's first fatellite, made at the different obfervatories in Europe, fince the year 1765; including the computed times of thefe phafes."
In the 11th Article, a method is given by Francis Maferes, Efq; of finding the value of an infinite féries of decreafing quantities of a certain form, when it converges too flowly to be fummed in the common way, by the mere computation and addition or fubtraction of fome of its initial terms.'-In an instance of a computation of this kind by the common way, quoted by the Author from a letter of Sir Ifaac Newton's, Sir Ifaac obferves, that to compute the value of the feries exact to, 20 decimal places of figures, there would be occafion for no fewer than five thousand millions of its terms; to compute which, would take up above a thousand years -Methufelah himself, in fhort, must leave the matter to his defcendents :-but the Author exhibits a differential feries, better adapted to us poftdiluvians, and which abridges the computation in a very great degree and he gives two examples which illuftrate his method, and fully prove its ufefulnefs."
An equally ingenious inveftigation forms the fubject of the 15th Article; in which Mr. Landen propofes a new theory of the rotatory motion of bodies affected by forces difturbing fuch motion; referving the application of this theory to the motion. of the earth's axis, to a future opportunity.
In the 12th Article, the Rev. Mr. George Coftard gives a new interpretation of a paffage in Ebn Younes, an Arabian aftronomer; together with fome remarks upon it.
Article 1. Contains a very fingular and well-authenticated account, written by Dr. Mackenzie, and communicated to the Society by the Lord Privy Seal of Scotland, of a woman in the fhire of Rofs, now aged fomewhat above 30 years, who, in the year 1707, had lived four years without fwallowing the leaft perceptible portion of food, or even drink; except that, once in that time, fhe drank a fmall draught of a mineral water, and, about two years afterwards, fwallowed an English pint of common water. During this period fhe had, as will readily be imagined, fcarce any fenfible evacuation. Notwithftanding this long abftinence, her countenance, fays Dr. M. was clear and pretty fresh, her features not disfigured nor funk; her fkin felt natural both as to touch and warmth; and, to my aftonishment, when I came to examine her body, for I expected to feel a fkeleton, I found her breafts round and prominent, like thofe of a healthy young woman; her legs, arms, and