MICROTASIMETEB. 462 MIDDELBTJRG. metron, measure). An instrument invented by Thomas A. Edison in 1877 for the purpose of measuring very minute variations of tempera- ture or moisture. The action of the apparatus depends on the effect wliieli the pressure of an expanding rod has upon the electrical resistance of a piece of carbon jjlaccd in tle circuit of a galvanic battery. A rod of vulcanite is used as the expanding element when it is desired to em- ploy the instrument to ascertain slight variations in the heat vibrations coming from any object, as the sun, or a gas or electric light. This rod is adjusted in a strong frame kept at an equable temperature, so that no expansions or contrac- tions shall exert any influence except those which take place in the vulcanite rod itself. In the chamber which receives one end of this rod or plate there is placed under a follower or slide a piece of carbon, which becomes compressed with great force upon the expansion of the vulcanite rod. If radiant heat is to be measured, a large fumiel is placed in front of the ajiparalus to gather the rays and throw them upon the rod or plate. When the rays increase in intensity the rod expands, compresses the button, and changes its resistance, the variation of which is indicated by a galvanometer. The instrument was used to ascertain the variations in the radiation from the sun during the solar eclipse of July 28, 1878. It may also be used to note the variations taking place on a day when clouds are passing across the sun's disk, or when the transmission of its rays is aflfccted by increase or decrease of moisture. It may be used as a delicate hygrometer by substituting in place of the vulcanite rod a body containing gelatin, which expands under the intluence of moisture. The chief disadvantage possessed by this instru- ment is that the carbon does not regain its orig- inal resistance after the ])rcssure is removed. Modern micro-radiometers and bolometers are, in addition, far more sensitive and are usually em- j)loyed for the measurement of radiation, MI'CROTOME. See Microscope, and Plate of Mi( Rciscori:. MI'DAS ( Lat., from Gk, MiSaj) , A common name of the more ancient Phrygian kings, of whom Midas, the son of Gordius and Cybele, is the most famous. According to one legend he captured 8ilenus by mixing wine with the water of the fountain at which the god drank, and thus secured for himself the wisdom of the god. Herod- otus tells this story as .Iace<lonian, but later writers transferred it to Phrygia. Another ver- sion, told by Ovid, rclat<'s that he restored Si- lenus to Dionysus, and wlien asked by the god to name his reward, prayed that whatever he touched might become gold, from which so great inconvenience ensued that he was glad to get himself relieved from the burden by washing, at the command of the god, in the Pactolus, the sands of which became thenceforth productive of gold. Another legend represents him as having offended Apollo by assigning the prize in the musical contest to Marsyas. or in later versions to Pan, and as having therefore been endowed by him with a pair of ass's ears. These, con- cealed under his Phrygian cap, were known only to his barber, who dared tell no man. but, unable to contain his secret, wliisiwred it 1o the earth. His precaution, however, was vain, for the reeds which sprang up at this spot, as they rustled in the wind, proclaimed the news to the world. Midas seems an ancient Phrygian nature-god, probably conceived, like Silenus and other similar fructifying deities, in animal form, but transformed by Greek story- tellers. The storv of the ass's ears is a common folk-tale. MI'DAS, A genus of marmosets ; but some- times the special name of the nuirakina (Midas rosniid ) . ."^ee M.k.moset. MIDDELBtTRG, mId'd'l-boorG. The capital of the Province of Zealand, Netherlands, situated on the island of Walcheren (Map: Xctherlands, B 3). It is connected with the sea by a canal five miles long, which admits ships of heavy burden. The city is surrounded by a broad canal, and has handsome houses, ornamented with gardens ; the canals and streets are shaded with trees. The town house, built in the six- teenth century, has a beautiful tower, and is decorated with twenty-five colossal statues of counts and countesses of Holland. At the be- ginning of the thirteenth century an abbey was founded here, which was later enriched by Wil- liam II., Count of Holland and Zealand. The buildings are now occupied as the meeting place of the Provincial States. Tlie new church con- tains the tomb of the naval heroes J. and C. Evertsen, and a monument to the German King William of Holland. The town possesses a provincial library, a giimnasium, a high school, and a normal school, and is the seat of several learned societies, with important collections of antiquities and objects of local interest. The city's commerce was formerly very large. It has some inland trade in grain, potatoes, and madder, and manufactures of cotton goods. Population, in 1892, 17,500; in 1000, 18,837, Middelburg was a llanse town in the Middle .ges. having received ils cliartcr in 122"). In 1574, during the war for independence, it was captured by the Dutch from the Spaniards after a siege of two years. It suffered heavily during the wars between England and France in the beginning of the nineteenth century. MIDDELBURG, Paul of (144.5-1.534). A Dutch nialhcMiatician, born at Middelburg, Avhence his name. He studied at the Uni- versity of Louvain, took orders, became canon of .Saint Barthelemy at Middelburg, and also taught mathematics, medicine, philosophy, and theology there. For having expressed himself regarding the faults of his fellow-citizens, he was banished froijj the town. He went to Lou- vain, where he lectured on mathematics so suc- cessfully that the Grand Council of Venice of- fered him the chair of mathematics at Padua. By 1484 he was at the Court of Francesco Maria della Rovere, Duke of Urbino, to whom he became physician anil by whom he was appointed to the abbacy of Castel Durante. It was also at the instigaliim of the Duke that he was elected Bishop of Fossondirone in 14114. In l.')13 he presided at the I'iftli Lateran Council (l.')12-17), where he spoke on the necessity of a revision of the existing calendar, later under- taken by Gregorv' XIIl. He was esteemed the first mathematician of his day. His publications include: T'rnrticn <lr I'nrrin Conuli llnlionibim (1484): Epistoln A polor/cl itii Mrifjistri I'niili do Middrlbiirpo (1487), in which he answers vari- ous objections rai-sed by mathematicians against
