180 



POPULAR SCIENCE NEWS. 



[December, 1S89. 



till they were quite hot ; the nuts were then 

 screwed up tight against the walls, and the 

 rods allowed to cool. In so doing, they con- 

 tracted, drawing the walls towards a perpen- 

 dicular position. This operation was repeated 

 several times, until the walls were once more 

 vertical, in which position they have remained 

 to the present time. 



[Orig^inal in The Popular Scii-nce jV" ws.] 



THE SCIENTIFIC KNOWLEDGE OF THE 



ANCIENT GREEKS AND ROMANS. 



BY JOHN C. ROLFE, PH. D. 

 I. 



That we owe a great deal of our mathematical 

 knowledge to the results reached by the ancients, is 

 a familiar fact. It may not be so generally known 

 that they applied their knowledge of mathematics 

 to accomplishing practical results in the different 

 departments of experimental science, and that many 

 .scientific appliances which are commonly supposed 

 to be the inventions of modern genius, were wholly 

 or partly anticipated by them. 



In the department of mechanics they may have 

 learned a great deal from the nation that taught 

 them so much in other directions, the Egyptians, 

 who must have acquired a great deal of knowledge 

 in that line. The first Greek to whom independent 

 mechanical inventions are attributed is Archytas 

 of Tarentum, who was also distinguished as a gen- 

 eral and a philosopher. He lived about 400 B. C, 

 and was therefore a contemporary ot Plato. Many 

 of his inventions were merely mechanical toys or 

 curiosities. Among these was a flying wooden dove, 

 which excited great wonder and admiration. But 

 he applied his talents to more serious. and valuable 

 ends, if those authorities are to be trusted who 

 credit him with the invention of the pulley and 

 screw. The first Greek to make mechanical princi- 

 ples the object of thorough scientific investigation 

 ■was Aristotle. We are told that he knew the prin- 

 ciple of the parallelogram of forces, for the special 

 case of right-angled components, and the law of 

 virtual velocities. His knowledge of physics was, 

 however, more theoretical than practical. 



Easily first among ancient Greek scientists is 

 Archimedes, of Syracuse in Sicily, who was born 

 about 287 B. C. He possessed inventive genius in 

 a degree never excelled, except, perhaps, by Newton. 

 The story is a familiar one that the discovery of the 

 adrflixture of silver in a crown which Hiero had 

 ordered to be made of pure gold, was suggested to 

 him by the overflowing of the water when he stepped 

 into a bath, and that he was so pleased that, forget- 

 ting to put on his clothes, he ran through the streets, 

 shouting, "Eureka!" ( "I have found it ! ") This 

 complete abstraction from outward things reminds 

 one of the stories of Newton sitting a great part of 

 the day haff-dressed on his bed, while composing 

 the Principia. Archimedes was the pioneer in the 

 studyof statics, and his theory of the lever was the 

 basis of that department of mechanics until the time 

 of Newton , while no important addition to the 

 principles of the equilibrium of fluids and floating 

 bodies, as laid down by him, was made until the 

 publication of Stevin's researches in 1608. 



His greatest fame in ancient times was due to his 

 inventions of implements of war. In the Second 

 Punic War, while Marcellus was besieging Syracuse, 

 -he is said to have set fire to the Roman ships by the 

 sun's rays, reflected from a series of mirrors. This 

 statement, which is not mentioned by the historians 

 Polybius, Livy, or Plutarch, has been much dis- 

 cussed and written about in modern times. It is 

 now generally regarded as a fiction, though one i 



investigator, Buffum, while prei)aring a dissertation 

 on the subject, succeeded in igniting wood at a dis- 

 tance of 150 feet, by a combination of 148 plane 

 mirrors. Of far greater real importance was the 

 invention of "Archimedes' screw," which he devised 

 for the jiurpose of pumping water from the hold of 

 a great .ship which he had built for Hiero. This 

 instrument is also said to have been used by the 

 inhabitants of lower Egypt for irrigating their land. 

 Another celebrated invention of Archimedes was a 

 sphere, representing by hydraulic power the move- 

 ments of the heavenly bodies ; but of this, unfor- 

 tunately, we have no description. 



Next in rank to Archimedes were Ktesibios and 

 Heron — or Hero, as his name is commonly written. 

 The former was probably born in Askra, in Boeotia, 

 in 150 B. C. ; according to others, at Alexandria, a 

 hundred years earlier. He invented a clepsydra, or 

 water-clock (which must have been of a complicated 

 mechanism, since the hours were of different lengths 

 at different seasons), and a water-organ. He was 

 the first to discover the elastic force of the air, and 

 to use it as a motive power. His pupil, Heron, was 

 more famous than his teacher, and was the author 

 of a number of brilliant inventions, for which he 

 has only in comparatively recent times received 

 credit. His name is well known from the familiar 

 pneumatic experiment called "Hero's fountain," in 

 which a jet of water is maintained by condensed air. 

 He also has the credit of inventing the first "steam- 

 engine," which acted exactly on the principle of 

 "Barker's mill," except that steam, and not water, 

 was the motive power. It consists of a boiler, hav- 

 ing arms with lateral orifices, which were capable of 

 revolving around a vertical axis ; the steam issued 

 from the orifices, and the uncompensated pressure 

 upon the parts opposite these turned the boiler. He 

 invented a double force-pump, used as a fire-engine, 

 and various other applications of the elasticity of 

 air and steam. He did not use steam power for the 

 performance of definite mechanical work. This 

 was first done by Anthemius, of Tralles in Lvdia, 

 who lived in the time of Justinian. Heron also 

 gave his attention to the invention of mechanical 

 toys and curiosities, and wrote a book on How to 

 Make Automata. Among his devices of this kind 

 are recorded a self-lighting fire for sacrificial offer- 

 ings, and an appliance for representing thunder in 

 theatrical performances. 



Anthemius, who has been mentioned above, was 

 not only a famous mathematician and architect, but 

 somewhat of a practical joker. On one occasion he 

 is said to have arranged cauldrons of water in a 

 lower room of his house, each vessel being covered 

 with the wide mouth of a leathen tube, which was 

 conducted to the attic of his next-door neighbor, 

 Zeno, against whom he haJ a grudge. The water 

 was heated, and the steam, rising into the confined 

 space under the roof, shook the adjacent house like 

 a slight earthquake, much to the amazement of 

 Zeno and his family. At another time, when Zeno 

 had friends to dine with him, the company at 

 the table were startled by the dazzling light flashed 

 into their faces by mirrors arranged for the purpose 

 by the waggish Anthemius, while frightful noises, 

 accompanying the blaze, suggested a sudden thun- 

 der-storm. 



Philon of Byzantium, who lived some time bel'ore 

 Heron, understood that air could be compressed or 

 expanded, and explained correctly the working of a 

 cupping-glass. 



The foremost Roman in this branch of science 

 was Vitruvius, the celebrated writer on architecture. 

 His birthplace is not known; he lived during the 

 first century B. C. He invented a hoisting 

 machine, which seems to have united the prin- 

 ciples of the pulley and the windlass, and an 



odometer which measured the distance traversed on 

 foot, or in a vehicle. The latter was practically the 

 same in principle as the pedometers and cyclo- 

 meters of the present day. He also knew and made 

 practical use of the fact that water rises to the same 

 height in communicating tubes of different shapes 

 and dimensions. Frontinus, who lived in the time 

 of Vespasian, wrote a work on The Aqueducts of the 

 City of Rome. In the course of his investigations, 

 he was the first to observe that not only the size of 

 the outlet, but also the elevation of the surface of 

 the water above it, regulated the amount discharged 

 in a given time, thus enrolling himself among the 

 predecessors of Torricelli. 



The grammarian Priscian, who lived at the end 

 of the fifth century of our era, is said to have 

 invented an hydrometer, which was, however, 

 limited to determining which of the two fluids 

 examined at the same time was the heavier. 



The discoveries of the ancients in other depart- 

 ments of physics will be considered in another 

 paper. 



4«> 



INDUSTRIAL MEMORANDA. 

 Ancient Specimens of Iron. — The oldest pieces 

 of wrought-iron now known are probably the sickle 

 blade found by Belzoni under the base of the sphinx 

 in Karnac, near Thebes; the blade found by Colonel 

 Vyse, embedded in the masonry of the great pyra- 

 mid, and the portion of a cross-cut saw exhumed at 

 Nimrod by Mr. Layard, — all of which are now in 

 the British Museum. A wrought bar of Damascus 

 steel was presented by King Porus to Alexander the 

 Great, and the razor steel of China for many centu- 

 ries surpassed all European steel in temper and 

 durability of edge. The Hindoos appear to have 

 made wrought-iron directly from the ore, without 

 passing it through the furnace, from time immemo- 

 rial, and elaborately wrought masses are still found 

 in India, which date from the early centuries of the 

 Christian era. 



Fuller's Earth. — Fuller's earth is an unctuous 

 sort of clay, much of it kaolinite, useful in fulling 

 cloth from its property, common to aluminous 

 earths, of absorbing oil and grease. The variety ol 

 clay is preferred which falls to pieces when put in 

 water, making a slight crackling sound. Its colors 

 are various shades of yellowish, greenish, bluish 

 brown, and gray; lustre dull, but appears greasy 

 when rubbed. It is not now esteemed as of much 

 value as formerly, soap having taken its place. In 

 England it used to be so highly valued that its ex- 

 portation was prohibited by law. When used it 

 was first dried in the sun or by fire, and then thrown 

 into cold water. The powder thus fornied was 

 sorted, by washing, into coarse and fine qualities, 

 the former of which was applied to inferior, the 

 latter to superior cloths. 



A Railway from London to India. — It is 

 reported that Sir Edward Watkin has submitted a 

 proposal for a gigantic railway project to the Secre- 

 tary of State for India. The railway is to extend in 

 one unbroken line from London to India ria Kurra- 

 chee. The channel tunnel is, of course, to form a 

 part of the scheme, though not an absolutely essen- 

 tial part of it, since the start could be made from 

 Calais or Boulogne. The railway would proceed 

 direct to Gibraltar, using the existing lines as far as 

 possible, and here would be introduced the novel 

 feature in the line. This would be a vast broad- 

 beamed boat capable of taking on board the entire 

 train as it arrives at Gibraltar, and delivering it on 

 the rails at Tangiers. Here the line would strike 

 eastward, keeping along the north coast of Africa, 

 touching at Egypt, and proceeding by the Persian 

 Gulf to Kurrachee, where it would join the Indian 

 railway system. 



