atoms, which either saturate the electro-negative element or link hydrogen to it, as the case may be. Thus, sulphur, an electro-negative element, forms a series of acids according to the valence displayed by it in the several cases, and according to the part the oxygen of the compound plays, whether simply linking or partly linking and partly saturating. We will give the formulas and the molecular structure of this set as illustrative of the class of acids referred to: Hyposulphurous Acid (Hydro-sulphurous of Schützenberger), H2SO2 or H-0-S-O-H, Metals which are ordinarily quite strongly electropositive may in the presence of a very strong base figure as electro-negative or acid-forming in the combinations with these strong bases. Thus, the evolution of hydrogen from the action of zinc upon potassium hydrate solution is explained on the assumption of the formation of a potassium zincate or the solution of aluminum hydrate in strong alkali by the formation of an alkaline aluminate. The same metal is sometimes assumed to exist in both electro-positive and electronegative conditions in one combination. Thus, red lead, which, when decomposed by nitric acid, yields lead in which the negative group is SO2, and the oxygen has nitrate and lead peroxide, is considered to be a plumbic only the linking function. 0-H 0-H, plumbate or compound of dyad lead as base and tetrad lead as acid-forming element. A similar case is also found in the case of antimony, which is generally electro-negative, but forms a very stable compound Sb2O, timonic acid HSbO1. in which the negative group is SO3, and the oxygen is (SbSbO,), antimony antimonate, derivable from anpartly saturating and partly linking oxygen. Sulphuric Acid, H2SO4 or 0=-0-H, Organic acids, frequently very complex in formula, may still be brought under the simple definition of acids given above. Indeed, the definition may be in which the negative group is SO, and the oxygen is made still narrower in their case. They are compounds partly saturating and partly linking. Other common acids of this class are of electro-negative groups with replaceable hydrogen, or rather with hydroxyl, as oxygen always links the hydrogen to the rest of the formula. They are made more complex, however, by the fact that these electronegative groups contain the same elements, carbon, hydrogen, and oxygen, as other groups acting electropositive, and are indeed formed from these latter by oxidation. So that an organic acid is distinguished by its containing an oxidized radical as distinguished from the alcohol or unoxidized radical, which acts electro-positive or basic. Thus, acetic acid C2H2O.OH is derived by oxidation from ethyl alcohol C2H.OH and benzoic acid CH.CO.OH from benzyl alcohol CH5. CH2OH. The molecular structure of this oxidized radical may vary very greatly, but its hydrate will still be an acid. Indeed, we may have two acids of the same ultimate formula, the sole difference bedized radical are differently arranged in the two. Thus, tween them being that the atoms constituting the oxiwe have two varieties of lactic acid CHO, the molecular formula of the one (the lactic acid of fermenCH3 CH.OH, Со.он In all these cases the hydrogen of the acid is connected to the electro-negative element by oxygen, constituting with it the group hydroxyl. Upon the number of hydrogen atoms so connected, or, in other words, the number of hydroxyl groups, depends the basicity of the acid. If hydrogen occur in the formula not replaceable by metal, we assume that it is not tation) being CH. OH, so connected. Such cases are common among organic acids when the hydrogen either belongs to the electronegative group itself or is attached to it as characteristic of the class of compounds called aldehydes, and hence is called aldehydic hydrogen. Among inorganic while the other (sarco-lactic acid) is CH2. acids we have two compounds that probably are of this latter character. They are hypophosphorous and phosphorous acids. In the case of these two acids the basicity of the acid does not agree with the number of hydrogen atoms they contain. Thus, hypophosphorous acid H3PO, is only monobasic, and phosphorous acid H.PO, is dibasic. In explanation of this anomaly their structural formulas are written respectively, when the number of hydroxyl groups at once shows the true basicity. A third class of inorganic acids are those in which the characteristic or fundamental element is not always electro-negative, but in its union with oxygen forms groups either electro-negative or electro-positive, according to the valence displayed by it in the particular case. Thus, chromium may form electro-positive or base-forming groups in the case of its lower oxides, or an electro-negative group when occurring as chromium trioxide CrO3. Examples of this kind are the chromates, which are the salts of chromic acid HCrO4; the manganates, derived from manganic acid H2MnO,; the permanganates, derived from permanganic acid HMnO.; the stannates, derived from stannic acid H„SnO3. CH2. OH Со. он been sometimes assumed to be characteristic of an The presence of the group CO.OH (carboxyl) has organic acid, but it is now admitted that this is not essential. Whether an organic hydrate is to act as alcoholic (or basic) or as acid, seems to depend simply on whether the hydroxyl attaches itself to a carbon atom already linked to oxygen or not. The oxygen with the carbon atom and the hydroxyl may make the group CO.OH, or it may be otherwise grouped. (For the secondary characters of acids, and also the physical tests by which they are generally recognized, see original article on ACIDS.) (S. P. S.) ACKNOWLEDGMENT, in law, the act of one who has executed a deed in going before some competent officer designated by statute and declaring the same to be his act and deed. The term is also used to indicate the certificate appended by the officer to the deed, which sets out the manner and fact of the acknowledgment. In England it is not the practice to acknowledge deeds; in the United States the custom is universal. The functions of an acknowledgment are in the United States twofold: (1) to authorize a deed to be offered in evidence without further proof of its execution; (2) to enable it to be recorded. 28 The power to take acknowledgments is by law vested | at All Souls. In 1848 he took the degree of M.D. at Christ The usual form of acknowledgment is for the person executing the deed to appear before the appropriate officer and to declare that the instrument is his act and deed. In most of the States, however, the acknowledgment of a deed by a married woman is a somewhat The woman is examined more elaborate ceremony. separate and apart from her husband, and declares that the deed is her own voluntary act, without any coercion or compulsion on her husband's part. In order to entitle a deed to be put in evidence with out further proof of its execution, or in order to enable it to be recorded, the certificate of acknowledgment must affirmatively show that all the requisites of the particular statutes in force in the State have been substantially complied with. The term acknowledgment" is also used in law to indicate an admission, particularly an admission of a debt due, so clear, explicit, and unconditional as to remove the bar of the statute of limitations. (L. L., JR.) ACLAND, LADY HARRIET (1750-1815), was a daughter of the earl of Ilchester, and was born Jan. 3, 1750. Her maiden name was Christiana Henrietta Caroline Fox Strangeways, but after her marriage in Sept., 1770, to John Dyke Acland, eldest son of Sir Thomas Acland of Devonshire, she was generally known as Lady Harriet Acland. Her husband was a member of Parliament for Callington, Cornwall, and in 1774, while still holding his seat in Parliament, entered the army. Becoming major of the Twentieth Foot in the next year, he was chosen by Gen. Burgoyne to accompany his expedition against the American colonies. Reaching Canada in June, 1776, Major Acland left his wife in Montreal, but she twice rejoined him in camp, and nursed him till restored to health. Then, refusing to be separated from him, she accompanied the advance of the army, though her husband's command was at the front. At the second battle of Saratoga, Oct. 7, 1777, he was shot through both legs and taken prisoner. As soon as she heard of his capture she obtained a letter from Gen. Burgoyne, and, accompanied by Rev. Edward Brudenel and a few others, sailed down the Hudson to the American lines. She was courteously received, and a few days later Gen. Gates sent her to Albany, whither her husband had been conveyed. When he recovered they visited New York and formed very favorable impressions of the people. Major Acland, being exchanged, returned to England, and in 1778 he fought a duel at Bampton Down with an officer who had aspersed the character of the AmeriAt the time of the duel he caught a severe cold, which terminated in a fever, and he died at Pixton Hall, Oct. 31, 1778. Lady Harriet never married again, and through the rest of her life could not refer In her youth she was to her husband without tears. noted for gracefulness and delicate beauty; in later life she is said to have suffered from cancer, though she concealed the fact till her death, which took place at Tetton, July 21, 1815. Her Letters and Journals, giving an account of her experiences in America, have been published. For a long time her adventures furnished a favorite subject for pen and pencil, and several romantic additions were made to her story without foundation in fact. One of these was, that after the death of Major Acland she was married to the chaplain who had escorted her from the British to the American army. (See articles by William L. Stone in the Magazine of American History, iv. 449, and in Lippincott's Magazine, xxiv. 452.) cans. ACLAND, HENRY WENTWORTH, M. D., F. R. S., ACONITINE. Aconitine, as met with in pharmacy, is of somewhat uncertain composition, the name having been applied to an amorphous alkaloid, or at best to a mixture of amorphous and crystallizable bases, extracted from Aconitum napellus and from mixtures of that and other species. 43 According to Wright, who with several colaborers C33H43NO12 + H2O = C7H6O2 + C26H39NO11. Both of these alkaloids, aconine and pseudaconine, Aconitum heterophyllum, lastly, contains atisine, an amorphous alkaloid of intensely bitter taste. Brough(S. P. S.) ton, its discoverer, assigns to it the formula C46H7N2O5. The drug is devoid of acridity and does not contain aconitine. ACOUSTICS. To the statement of the principles See Vol. I. and facts of the science of ACOUSTICS, as p. 93 Am. given in the Encyclopædia Britannica, the Edin. ed.). eries should be added: ed. (p. 100 following important details and new discov Atmospheric Influence.-Experiments in signalling with sonorous instruments on the coast during fogs have led to a preference for the siren over the trumpet, and for the trumpet over the whistle. They have disproved Perfect stillness the notion that sounds travel farthest in fine weather. On the contrary, sounds are heard at greater distances and uniform density and temperature are found to through fog, snow, hail, or rain. The velocity of sound (which is be most favorable conditions for the transmission It is sometimes of sound-waves. seven hundred times greater than that of a breeze) is not sensibly affected by the wind. conveyed better against the wind or at right angles with it than when both proceed in the same direction. Sound travelling with the wind is refracted to the earth, and travelling against it is elevated several hundred feet. Sound so lost may be heard again far off, being returned to earth by a contrary current, or (from the spreading of the tone) it may arrive from another point. Sounds unheard on the deck of a vessel may be clearly distinguished on the masthead. This spreading of the tone in all directions on the horizon is so marked a peculiarity that a fog-trumpet is heard nearly as well at equal distance behind as in front. Concave reflectors therefore are of little service. During early experiments the most conflicting results were frequently obtained and generally accepted theories disproved. Prof. Tyndall, on finding the sound obstructed in clear weather, assumed that streams of air differently heated or saturated in different degrees with aqueous vapors rendered the atmosphere flocculent to sound; that invisible acoustic clouds incessantly passed through the air, intercepting the sound, wasting it by innumerable reflections, as light is wasted in an ordinary cloud; and therefore that days of extraordinary acoustical transparency may be followed by days of extraordinary acoustical opacity. Archibald Forbes, in My Experiences of the War between France and Germany (vol. ii. pp. 285-289), noted that the cannonading in the distance, which was well heard on cold, damp, and foggy days, in extremely fine weather was unheard. Such stillness reigned that it was generally believed the firing had ceased. it Prof. Henry, who for many years experimented on fog-signalling, and gave us the best fog-signals in the world, recorded his doubt of the above conclusions that the screening effects were due to abnormal conditions, and believed that sound will pass through these "regions of silence" freely enough in an opposite direction. As his experiences from 1865 to 1877 were not given to the world, but recorded in purely official documents, may be well to state that in the appendix to the report of the Lighthouse Board for the fiscal year ending June 30, 1874 (p. 116), he says that a flocculent condition of the atmosphere, due to the varying density produced by the mingling of invisible aqueous vapor, is a true cause of obstruction in the transmission of sound-a fact borne out by the principles of wave-motion as well as by experiment-but that he is far from thinking this to be the efficient cause of the phenomena under consideration. That a flocculent condition of the atmosphere should slightly obstruct the sound is therefore not difficult to conceive, but that it should obstruct the sound-ray in one direction and not in an opposite, or in a greater degree in one direction than in another, the stratum of air being the same in all cases, is not credible. Aerial Echoes. It is believed by some that the strong and prolonged aërial echoes are produced in the clearest air by acoustic clouds; and it is maintained by others that such echoes have been clearly heard when there was no acoustic cloud in the direction of the prolongation of the axis of the fog-trumpet; that these echoes have been heard in all weathers and under widely differing circumstances; that they become fainter, and not stronger, when approached, although they are more continuous, increasing from five to twenty minutes; and that these, in common with many other phenomena said to have been observed, await fuller investigation. The atmosphere evidently exercises a selective choice upon the waves of sound continuously, sometimes favoring tones of deep pitch and sometimes those of greater altitude. Harmonic Echoes-It may be an explanation of harmonic echoes that the fundamental tones are weakened or lost, while the overtones are heard in full strength or reinforced. When the original sound is required to be of a character that is known to be rich in such overtones, and the intervening space is a wooded valley, this view As a rule, these speeds are diminished by augmented temperature. Iron, within certain limits, is an exception. At 100° C. it reaches 17,386; at 200° C. it falls to 15,483. The double echoes in coal-mines are due to varying velocities. The velocity of sound in coal is estimated at 7000 feet per second. The sound of each stroke of the miner being transmitted through the coal, and also much more slowly through the air, has given rise to the story of his ever-heard but never-seen colaborer. Sound in Buildings.-Annoying echoes in buildings may be modified by the hanging of curtains or the use of matting to absorb the tone at those points from which it is reflected. The new cathedral of St. Finn Bar at Cork in Ireland, the nave of which is of great height in proportion to the width, had a troublesome echo. Several thin wires, barely visible from below, were stretched across the building at certain points, and proved to be perfectly successful in destroying the echoes. They are now commonly used for this purpose, for the experiment is easily made, and the number of wires may be readily increased until the adjustments are satisfactory. At the new cathedral of St. Patrick in New York six wires, near the west gallery, are sufficient. In buildings intended for music the ceiling should not meet the wall at right angles, and other means should be taken to prevent sudden checks to the progress of the sound-waves and the consequent rebounding. Nor should the ceiling be perfectly flat; it should have the form of the inverted hull of a ship or the roof of the mouth, which is a resonant air-cavity. A certain amount of resonance being desirable, although echoes are distressing to both musicians and orators, it is well to arrange to have it in excess when the hall is empty, for the dresses of the audience absorb very much tone. The erection of a gallery across the hall opposite the stage will sometimes destroy an echo, or a speaker by directing his voice under such a gallery may evade it. Wellpractised speakers and singers learn to adapt themselves to rooms by so directing their voices to particular points. Speakers who are free to use whatever tones they choose sometimes adapt the pitch of their voices to the various halls in which they speak. A clergyman accustomed to his own church preaches therein with less effort than in a strange building. Although much stress is laid upon the advisability of having music-rooms planned in accordance with particular proportions as regards length, breadth, and height, so that all the dimensions may be multiples of some unit of length, yet it appears that the influence of a building in deadening or reinforcing and enhancing tones depends as much upon the materials used as upon the form adopted. Choir-singers attached to various cathedral establishments in England have frequently noticed the good effect of music sung in almost any old building in the precincts, whatever its proportions. It seems to have escaped observation that in all such cases the buildings are of solid stone or good brick with mortar so well made as to be stronger than the bricks themselves, and the wood is extremely hard and close-grained. In a diving-bell sounds are very loud, on account of the compression of the air. The intensity of sound 30 depends on the density of the air where it is produced, and not on that where it is heard, unless the latter airvolume be the denser. A partly deaf person will hear better in a gallery than on the ground floor, whether the speaker be elevated or not. Sound Compared with Light and Water.-There are analogies between the laws that govern the progress of sound, light, and water. Sound in its uniformity of speed and in its decay by radiation resembles light, but in its mode of deflection, reflection, and absorption it partly resembles light and partly water. Sound, like water, can be conducted through tubes, etc., as light cannot. Light travels in straight lines from its source, and consists of distinct impulses sucIn this it ceeding one another and forming waves. resembles sound. Waves of water, when they strike at a more acute angle than 45°, are not perfectly reflected. When they strike at a more acute angle than 30°, they seem to travel along the bank or other surface against which they have struck. Waves of sound, however, are not only reflected, but also radiated, and often reinforced, by the sympathetic vibrations of bodies which they strike while being transmitted. The mathematical theory of undulations shows that the waves of sound bend around obstacles, and produce more or less effect within the geometrical shadow, while light-shadows are more sharply defined. This may result from their difference of pitch, since we find that the acoustic shadows cast by notes high in pitch are more distinct than those cast by deep tones. Sound resembles light also in a property like translucency, since some bodies give passage to only a portion of the sound-waves. The Polarization of Sound.-Prof. S. W. Robinson of the Ohio State University, having examined the nature of vibrations in extended media, asserts that if they are produced from the action of a remote single centre of disturbance, they can only be longitudinal, even in light; that vibrations will be to some extent transversal when due to two or more centres of disturbance not in the same line, as when two or more independent co-existent systems of undulations combine into one, or when a simple system is modified by such lateral disturbance as a reflection or a refraction; that undulations to be in a condition called polarized probably consist of vibrations which are transversal, and that no necessity exists for assuming vibrations to be transversal in front of a polarizer. His method of experiment is ingenious, and the results are very interesting, but further experiments are necessary before a satisfactory knowledge of the matter can be gained. Prof. Robinson, however, believes that the longitudinal character of the vibrations of sound has been proved by the repeated reflections he gained from the surfaces of membranes separating coal A diminution in intensity was produced gas and air. according to the relative positions of the membranes, analogous to reflections of light from a series of glass plates. When the membranes used become, from any cause, too slack or too tense, the results are disappointing. Their tension must be carefully adjusted. The Note of a Building.-It frequently happens that an organ carefully regulated in every particular in the factory, and designed to fill with tone a given number of cubic feet in a church of which the materials and shape are known, on being erected in the edifice has one particular note reinforced in a remarkable degree, so that it seems almost impossible to reduce its power that it may be uniform in strength with others. This note is possibly one whose sound-wave is correlated to the unit of measurement of the building. Sensitive Flames.-The most sensitive flame is a conical one having a deep-blue base and yellowish apex, obtained from ordinary gas-jets by placing a wire gauze (having 32 meshes to the lineal inch) about two inches above a Sugg's steatite pin-hole burner and lighting the gas above the gauze. At the least noise the flame roars and sinks so as to become almost invisible. It dances well to an ordinary musical snuff-box, but is not par ticularly sensitive to other vowels than a and u. The Beats.-Players on stringed instruments and tuners Approach Caused by Vibration.-Prof. GuthrieChallis and Prof. J. Clerk Maxwell have experimented to determine the cause and conditions of the observed fact, that when a vibrating tuning-fork or vibrating disc is held near a piece of suspended cardboard the latter has a tendency to approach the fork or disc. This is not due to the establishment of permanent air-currents. The approach begins from distances far exceeding the range of Faraday's surface whirlwinds. The vibrating fork displaces air. The effect of apparent attraction is caused by atmospheric pressure which is due to pendulatory dispersion. The pressure of the air on the suspended body is less on the Mercadier's Music Register.-A wire suspended by side nearest the fork than on the opposite side. narrow strips of caoutchouc is soldered at one end to a small plate of brass which is placed between the sounding-board of a violin or other stringed instrument and the foot of the bridge. The other end is fixed to a heavy stand in such a manner as to communicate its vibrations to a feather which is also fixed to the stand. In this way the vibrations are of greater amplitude than they would be if the feather were attached directly to the wire. The feather is so placed as to record its motions on a smoked cylinder which may be its vibrations simultaneously on the cylinder as a chroturned by the hand. A tuning-fork is made to record may The resulting wave-marks nograph, so that the cylinder need not be turned with a uniform motion. measured with the aid of a micrometer. Stereoscopic slides have been employed by Preece and Stroh to throw into perspective the very complicated vibration-curves of sonorous bodies. be Miniature Whirlwinds.-If some lycopodium or other impalpable powder (such as that found in puff-balls or any fungus yielding very fine brown dust) be sprinkled with sand on a vibrating plate, it will collect at the very points that the sand avoids. Were the experiment performed in vacuo, the powder would mix with the sand, for it is the upward and downward movement of the air in obedience to the vibratory action that causes the dust to dance over those portions of the plate where the action is greatest, and eventually to subside in heaps away from the nodal lines. Recent Researches.-During the past ten years the science of acoustics has made very great advances. It has been demonstrated that the pitch of sounds is raised if the vibrating body is approaching the hearer, and vice versa. This is the basis of Prof. Doppler's theory of the colored stars. Prof. Mayer raised a fork a minor third by rapid rotation. A jet of water descending from a circular orifice is found to consist of a succession of drops which may be analyzed by the electric spark, and like flames be caused to emit a musical sound and respond to extraneous sounds. When a beam of sunlight falls upon lampblack, the particles, being thus heated, expand, and cause a contraction of the air-spaces or pores among them. When the light is cut off, the converse process takes place. The action is somewhat like that of repeatedly filling a sponge with water and squeezing it. Prof. Graham Bell made successful experiments with solids, liquids, and gaseous matter, the sounds produced being sometimes audible all round a large room. He found that the vapors of the following The resonator of Helmholtz has aided materially in substances were highly sonorous in the intermittent many forms of research. In value and use it is analo- beam: water vapor, coal gas, sulphuric ether, ammonia, gous to the microscope. The invention of the mega-amylene, ethyl bromide, diethylamene, mercury; and phone, microphone, topophone, and harmonic telegraph that the loudest sounds were obtained from iodine and of Elisha Gray, the translating phonograph, the elec- peroxide of nitrogen. tro-motograph, musical telephone, and the singing and speaking telephone by Edison, and the general use of telephones of varied forms and powers, form important steps of progress in applied acoustics. Actual Vibration Numbers.-The four methods of finding the actual vibration numbers of notes described by Dr. Robert Smith of Cambridge University in his elaborate treatise on Harmonics (London, 1759), and the formula given by Woolhouse in his work on musical intervals, are now superseded. They were set aside on account of their liability to errors which could not be easily eliminated. The siren of Dove, though valuable to acousticians for general use, is not sufficiently accurate or delicate for particular purposes. The names "thermophone," "photophone," and "actinophone" are applied to instruments for the production of sound by thermal, luminous, or actinic rays respectively. "Radiophone" signifies an apparatus intended for utilizing any form of radiant energy. When the color of the light is changed the sonority is also changed; thus, hard-rubber shavings, which will sing in red, orange, yellow, and green, refuse to sing at all in blue, indigo, or violet. Green silk will sing in red, but not in indigo. Coal gas, in common with iodine vapors, sings very lustily; hence the presence of firedamp may be thus detected. (S. A. P.). ACRELIUS, ISRAEL (1714-1800), a Swedish clergyman, author of a history of New Sweden, was born at When great exactness is required, the new chrono- Osteraker, Dec. 25, 1714. He graduated at the Uniscope of Schultz is employed. It consists of a metallic versity of Upsal, and was ordained in 1743. He was cylinder blackened by smoke, which is made to revolve appointed by the consistory of Upsal to the pastorate so close to a point attached to one of the prongs of a of the Swedish church at Christina (Wilmington), and tuning-fork that the vibratory motions of the latter may commissioned with the general charge of the Swedish be traced upon it. The cylinder is made to revolve by churches on the Delaware as their provost in June, machinery at uniform speed, although alterations in the 1749. He arduously devoted himself to his task, imrate of revolution would not vitiate the result. The proved the condition of his parish, attended to the afonly difference caused by such variations would be fairs of the other Swedish churches, preached in Swedish shown in the amount of space occupied by the curves and English, and collected much information on the state representing each vibration, and not the number of of the Lutheran churches in America. At a conferthese recorded in the given time. This chronoscope is ence of ministers at New Providence in 1753 he read a used during artillery practice at West Point. The fork Latin essay "On the Origin and Progress of the Gerbeing regularly excited, the pendulum of a clock is ar- man Evangelical Congregations in Pennsylvania and ranged so as to touch a spring and thus send an electric the Adjacent Countries," which was printed in the spark to the recording cylinder. By this device the twentieth volume of the Acta Historico-Ecclesiastica. vibrations that have been recorded in a given space of At his request he was relieved of his charge in time are marked off. The interval during which a can-America in 1756, and appointed to the pastorate of non-ball passes through two targets is similarly marked Fellingsbro in the diocese of Westerås in Sweden. He off by sparks, and the vibrations are counted afterwards died at Fellingsbro, April 25, 1800. After his return in like manner. There generally remains a fraction of to his native land he wrote the work that has given a vibration. By the aid of a micrometer this fraction him a prominent place among the early writers on is accurately measured on the cylinder, for each vibra- colonial history, Beskrifning Om De] Swenska tion may be, in the first place, divided into twenty Församlingars | Forna och Narwarande | Tilstand, parts, and each of these parts again into one hundred Uti| Det så kallade Nya Swerige, | Sedan | Nya Neparts. By thus subdividing one complete cycle or vibra- derland, | Men nu för tiden | Pensylvanien, samt nåsttion of a tuning-fork making 250 vibrations per second, liggunde Orter wid Alf-wen De la Ware, Wüst- Yersey calculations may be conveniently made in terms as small och New-| Castle County uti Norra America. Deas the five-hundred-thousandth part of a second. It is scription of the Former and Present Condition of the easy to see that by employing a fork of higher pitch Swedish Churches in what was called New Sweden, (say, B natural, the middle line of the treble staff, with afterwards New Netherland, but at the Present Time 500 vibrations per second) this interval of time could Pennsylvania, Stockholm, 1759.) The book does not be as easily subdivided into one million parts. In con- confine itself, as might be inferred from its title, to sequence of Prof. Mayer's discovery that a variation of ecclesiastical matters, but contains interesting chapters 1° Fahr. caused a difference of 0125 in a fork produc- on the political history and social state of Pennsylvania ing 256 vibrations per second, and a difference of 023 in and New Jersey, and is considered a valuable source another making 512 vibrations, and other slight varia- of authentic information. A portion of it was transtions, the fork is now frequently tested, and elaborate lated into English by Rev. Dr. Collin, the last Swedish contrivances are devised to prevent the slightest inac- rector of the churches on the Delaware, and was printed in the Collections of the New York Historical Society in 1841. The desire for an English translation of the whole work was at last gratified in 1874. The translation, made by Rev. Wm. M. Reynolds, was published under the joint auspices of the historical societies of Pennsylvania and Delaware, and forms the eleventh volume of the Memoirs of the Historical Society of Pennsylvania. curacy. Sound from Radiant Energy.-The photophone is an instrument for the production of sound, even from non-conductors of sound, by the action of an intermittent beam of white light. It is thus proved that sonorousness is a property of all matter. The loudest sounds are produced from substances in a loose, porous, spongy condition, such as cotton wool, worsted, fibrous materials generally, cork, sponge, etc., and also from those that have the darkest or most absorbent colors. ACROMYODI (Gr. ȧkoos, pointed; uvs, muscle), in ornithology, one of the primary divisions of the great |