The inventive genius of this century in the field of optics has not eclipsed the telescope and microscope of former ages. They were the fruits of the efforts of many ages and of many minds, although Hans Lippersheim of Holland in 1608 appears to have made the first successful instrument "for seeing things at a distance." Galileo soon thereafter greatly improved and increased its capacity, and was the first to direct it towards the heavens. And as to the microscope, Dr. Lieberkulm, of Berlin, in 1740, made the first successful solar microscope. As well known, it consisted essentially of two lenses and a mirror, by which the sun's rays are reflected on the first lens, concentrated on the object and further magnified by the second lens.

The depths of the stars and the minutest mote that floats in the sun beam reflect the glory of those inventions.

The invention of John Dolland of London, about 1758, of the achromatic lens should be borne in mind in connection with telescopes, microscopes, etc. He it was who invented the combination of two lenses, one concave and the other convex, one of flint gla.s.s and the other of crown gla.s.s, which, refracting in contrary ways, neutralised the dispersion of colour rays and produced a clear, colourless light.

Many improvements and discoveries in optics and optical instruments have been made during the century, due to the researches of such scientists as Arago, Brewster, Young, Fresnel, Airy, Hamilton, Lloyd, Cauchy and others, and of the labours of the army of skilled experts and mechanicians who have followed their lead.

Sir David Brewster, born in Scotland in 1781, made (1810-1840) many improvements in the construction of the microscope and telescope, invented the kaleidoscope, introduced in the stereoscope the principles and leading features which those beautiful instruments still embody, and rendered it popular among scientists and artists.

It is said that Prof. Eliot of Edinburgh in 1834 was the first to conceive of the idea of a stereoscope, by which two different pictures of the same object, taken by photography, to correspond to the two different positions of an object as viewed by the two eyes, are combined into one view by two reflecting mirrors set at an angle of about 45, and conveying to the eyes a single reflection of the object as a solid body. But Sir Charles Wheaton in 1838 constructed the first instrument, and in 1849 Brewster introduced the present form of lenticular lenses.

Brewster also demonstrated the utility of dioptric lenses, and zones in lighthouse illumination; and in which field Faraday and Tyndall also subsequently worked with the addition of electrical appliances. The labours of these three men have illuminated the wildest waters of the sea and preserved a thousand fleets of commerce and of war from awful shipwreck.

As ill.u.s.trating the difficulties sometimes encountered in introducing an invention into use, the American Journal of Chemistry some years ago related that the Abbe Moigno, in introducing the stereoscope to the savants of France, first took it to Arago, but Arago had a defect of vision which made him see double, and he could only see in it a medley of four pictures; then the Abbe went to Savart, but unfortunately Savart had but one eye and was quite incapable of appreciating the thing. Then Becquerel was next visited, but he was nearly blind and could see nothing in the new optical toy. Not discouraged, the Abbe then called upon Puillet of the Conservatoire des Arts et Metiers. Puillet was much interested, but he was troubled with a squint which presented to his anxious gaze but a blurred mixture of images. Lastly Brot was tried.

Brot believed in the corpuscular theory of light, and was opposed to the undulatory theory, and the good Abbe not being able to a.s.sure him that the instrument did not contradict his theory, Brot refused to have anything to do with it. In spite, however, of the physical disabilities of scientists, the stereoscope finally made its way in France.

Besides increasing the power of the eye to discover the secrets and beauties of nature, modern invention has turned upon the eye itself and displayed the wonders existing there, behind its dark gla.s.s doors. It was Helmholtz who in 1851 described his _Ophthalmoscope_. He arranged a candle so that its rays of light, falling on an inclined reflector, were thrown through the pupil of the patient's eye, whose retina reflected the image received on the retina back to the mirror where it could be viewed by the observer. This image was the background of the eye, and its delicate blood vessels and tissues could thus be observed. This instrument was improved and it gave rise to the contrivance of many delicate surgical instruments for operating on the eye.

The _Spectroscope_ is an instrument by which the colours of the solar rays are separated and viewed, as well as those of other incandescent bodies. By it, not only the elements of the heavenly bodies have been determined, but remarkable results have been had in a.n.a.lysing well-known metals and discovering new ones. Its powers and its principles have been so developed during the century by the discoveries, inventions and investigations of Herschel, Wollaston, Fraunhofer, Bronsen and Kirchoff, Steinheil, Tyndall, Huggins, Draper and others, that spectrum a.n.a.lysis has grown from the separation of light into its colours by the prism of Newton, to what Dr. Huggins has aptly termed "a new sense."

We have further referred to this wonderful discovery in the Chapter on Chemistry.

The inventions and improvements in optical instruments gave rise to great advances in the making of lenses, based on scientific principles, and not resting alone on hard work and experience. Alvan Clark a son of America, and Prof. Ernst Abbe of Germany, have within the last third of the century produced a revolution in the manufacture of lenses, and thereby extended the realms of knowledge to new worlds of matter in the heavens and on earth.

_Solarmeter._--In 1895 a United States patent was granted to Mr. Bechler for an instrument called a solarmeter. It is designed for taking observations of heavenly bodies and recording mechanically the parts of the astronomical triangle used in navigation and like work. Its chief purpose is to determine the position of the compa.s.s error of a ship at sea independently of the visibility of the sea horizon. If the horizon is clouded, and the sun or a known star is visible, a ship's position can still be determined by the solarmeter.

_Instruments for Measuring the Position and Distances of Unseen Objects._--Some of the latest of such instruments will enable one to see and shoot at an object around a corner, or at least out of sight. Thus a United States patent was granted to Fiske in 1889, wherein it is set forth that by stationing observers at points distant from a gun, which points are at the extremities of a known base line, and which command a view of the area within the range of the gun, the observers discover the position and range of the object by triangulation and set certain pointers. By means of electrical connection between those pointers and pointers at the gun station based on the system of the Wheatstone bridge, the latter pointers, or the guns themselves serving as pointers, may be placed in position to indicate the line of fire. By a nice arrangement of mirror and lenses attached to a firearm the same object may be accomplished. Similar apparatuses in which the reflectory surfaces of mirrors mounted on an elevated frame-work, and known as _Polemoscopes_ and _Altiscopes_ and _Range-Finders_, have also been invented, and used with artillery. But such devices may be profitably used for more peaceful and amusing purposes.

Born with the ear attuned to music and the eye to observe beauty, the hand of Art was to trace and make permanent the fleeting forms which melody and the eye impressed upon the soul of man.

In fact modern science has demonstrated that tones and colours are inseparable. Bell and Tainter with their _photophone_ have converted the undulatory waves of light into the sweetest music. Reversing the process, beautiful flashes of light have been produced from musical vibrations by the _phonophote_ of M. Coulon and the _phonoscope_ of Henry Edmunds.

Entrancing as the story is, we can only here allude to a few of those discoveries and inventions that have become the handmaidens of the art which guided the chisel of Phidias and inspired the brush of Raphael.

_Photography._--The art of producing permanent images of the "human face divine," natural scenes, and other objects, by the agency of light, is due more to the discoveries of the chemist than to the inventions of the mechanic; and to the chemists of this century. At the same time a mechanical invention of old times became a necessary appliance in the reduction of the theories of the chemists to practice:--The _Camera Obscura_, that dark box in which a mirror is placed, provided also with a piece of ground gla.s.s or white cardboard paper, and having a projecting part at one end in which a lens is placed, whereby when the lens part is directed to an object an image of the same is thrown by the rays of light focused by the lens upon the mirror, and reflected by the mirror to the gla.s.s or paper board, was invented by Roger Bacon about 1297, or by Alberta in 1437, described by Leonardo da Vinci in 1500 as an imitation of the structure of the eye, again by Baptista Porta in 1589, and remodelled by Sir Isaac Newton in 1700. Until the 19th century it was used only in the taking of sketches and scenes on or from the card or gla.s.s on which the reflection was thrown.

Celebrated chemists such as Sheele of the 18th century, and Ritter, Wollaston, Sir Humphry Davy, Young, Gay-Lussac, Thenard, and others in the early part of the 19th century, began to turn their attention to the chemical and molecular changes which the sunlight and its separate rays effected in certain substances, and especially upon certain compounds of silver. In sensitising the receiving paper, gla.s.s, or metal with such a compound it must necessarily be protected from exposure to sunlight, and this fact, together with the desire to sensitise the image produced by the camera, not only suggested but seemed to render that instrument indispensable to photography. Nevertheless the experiments of chemists fell short of the high mark, and it was reserved for an artist to unite the efforts of the sun and the chemists in a successful instrument.

It was Louis Jacques Mande Daguerre, born at Corneilles, France, in 1789, and who died in 1851, who was the first to reduce to practice the invention called after his name. He was a brilliant scene painter, and especially successful in painting panoramas. In 1822, a.s.sisted by Bouton, he had invented the _diorama_, by which coloured lights representing the various changes of the day and season were thrown upon the canva.s.ses in his beautiful panoramas of Rome, London, Naples and other great cities. Several years previous to 1839 he and Joseph N.

Niepce, learning of the efforts of chemists in that line, began independently, and then together, to develop the art of obtaining permanent copies of objects produced by the chemical action of the sun.

Niepce died while they were thus engaged. Daguerre prosecuted his researches alone, and toward the close of 1838 his success was such that he made known his invention to Arago, and Arago announced it in an eloquent and enthusiastic address to the French Academy of Sciences in January 1839. It at once excited great attention, which was heightened by the pictures produced by the new process. The French Government, in consideration of the details of the invention and its improvements being made public and on request of Daguerre, granted him an annuity and one also to Niepce's son.

At first only pictures of natural objects were taken; but in learning of Daguerre's process Dr. John William Draper of New York, a native of England and adopted son of America, the brilliant author of _The Intellectual Development of Europe_, and other great works, in the same year, 1839, took portraits of persons by photography, and he was the first to do this. Draper was also the first in America to reveal the wonders of the spectroscope; and he was first to show that each colour of the spectrum had its own peculiar chemical effect. This was in 1847.

The sun was now fairly harnessed in the service of man in the new great art of Photography. Natural philosophers, chemists, inventors, mechanics, all now pressed forward, and still press forward to improve the art, to establish new growths from the old art, and extend its domains. Those domains have the generic term of _Photo-Processes_.

Daguerreotypy, while the father of them all, is now hardly practised as Daguerre practised it, and has become a small subordinate sub-division of the great cla.s.s. Yet more faithful likenesses are not yet produced than by this now old process. Among the children of the Photo-Process family are the _Calotype_, _Ambrotype_, _Ferreotype_, _Collodion_ and _Silver Printing_, _Carbon Printing_, _Heliotype_, _Heliogravure_, _Photoengraving_ (relief intaglio-Woodburytype), _Photolithography_; _Alberttype_; _Photozincograph_, _Photogelatine-printing_; _Photomicrography_ (to depict microscopic objects), _Kinetographs_, and _Photosculpture_. A world of mechanical contrivances have been invented:--_Octnometers_, _Baths_, _Burnishing tools_, _Cameras and Camera stands_, _Magazine and Roll holders_; _Dark rooms_ and _Focussing devices_, _Heaters_ and _Driers_; _Exposure Meters_, etc. etc.

The _Kinetograph_, for taking a series of pictures of rapidly moving objects, and by which the living object, person or persons, are made to appear moving before us as they moved when the picture was taken, is a marvellous invention; and yet simple when the process is understood.

Photography and printing have combined to revolutionise the art of ill.u.s.tration. Exact copies of an original, whether of a painting or a photograph, are now produced on paper with all the original shades and colours. The long-sought-for problem of photographing in colours has in a measure been solved. The "three _colour processes_" is the name given to the new offspring of the inventors which reproduces by the camera the natural colours of objects.

The scientists Maxwell Young and Helmholtz established the theory that the three colours, red, green, and blue, were the primary colours, and from a mixture of these, secondary colours are produced. Henry Collen in 1865 laid down the lines on which the practical reduction should take place; and within the last decade F. E. Ives of Philadelphia has invented the _Photochromoscope_ for producing pictures in their natural colours. The process consists in blending in one picture the separate photographic views taken on separate negative plates, each sensitised to receive one of the primary colours, which are then exposed and blended simultaneously in a triple camera.

Plates and films and many other articles and processes have helped to establish the Art of Photography on its new basis.

Among the minor inventions relating to Art, mention may be made of that very useful article the lead _pencil_, which all have employed so much time in sharpening to the detriment of time and clean hands. Within a decade, pencils in which the lead or crayon is covered instead of with wood, with slitted, perforated or creased paper, spirally rolled thereon, and on which by unrolling a portion at a time a new point is exposed; or that other style in which a number of short, sharpened marking leads, or crayons, are arranged in series and adapted to be projected one after the other as fast as worn away.

_In Painting_ modern inventions and discoveries have simply added to the instrumentalities of genius but have created no royal road to the art made glorious by t.i.tian and Raphael. It has given to the artists, through its chemists, a world of new colours, and through its mechanics new and convenient appliances.

_Air Brushes_ have proved a great help by which the paint or other colouring matter is sprayed in heavy, light, or almost invisible showers to produce backgrounds by the force of air blown upon the pigments held in drops at the end of a fine spraying tube. Made of larger proportions, this brush has been used for fresco painting, and for painting large objects, such as buildings, which it admits of doing with great rapidity.

A description of modern methods of applying colours to porcelain and pottery is given in the chapter treating of those subjects.

_Telegraphic pictures_:--Perhaps it is appropriate in closing this chapter that reference be made to that process by which the likeness of the distant reader may be taken telegraphically. A picture in relief is first made by the swelled gelatine or other process; a tracing point is then moved in the lines across the undulating surface of the pictures, and the movements of this tracer are imparted by suitable electrical apparatus to a cutter or engraving tool at the opposite end of the line and there reproduced upon a suitable substance.

CHAPTER XXVII.

SAFES AND LOCKS.

Prior to the century safes were not constructed to withstand the test of intense heat. Efforts were numerous, however, to render them safe against the entrance of thieves, but the ingenuity of the thieves advanced more rapidly than the ingenuity of safe-makers. And the race between these two cla.s.ses of inventors still continues. For with the exercise of a vast amount of ingenuity in intricate locks, aided by all the advancement of science as to the nature of metals, their tough manufacture and their resistance to explosives, thieves still manage to break in and steal. The only sure protection against burglars at the close of the nineteenth century appears to consist of what it was at the close of any previous century--the preponderance of physical force and the best weapons. Among the latest inventions are electrical connections with the safe, whereby tampering therewith alarms one or more watchmen at a near station.

A cla.s.sification of safes embraces, _Fire-proof_, _Burglar-proof_, _Safe Bolt Works_, _Express and Deposit Safes and Boxes_, _Circular Doors_, _Pressure Mechanism_, and _Water and Air Protective Devices_.

The attention of the earliest inventors of the century were directed toward making safes fire-proof. In England the first patent granted for a fire-proof safe was to Richard Scott in 1801. It had two casings, an inner and outer one, including the door, and the inters.p.a.ce was filled in with charcoal, or wood, and treated with a solution of alkaline salt.

This idea of inters.p.a.cing filled in with non-combustible material has been generally followed ever since. The particular inventions in that line consist in the discovery and appliance of new lining materials, variations in the form of the inters.p.a.cing, and new methods in the construction of the casings, and the selection of the best metals for such construction.

In 1834 William Marr of England patented a lining for a double metallic chest, filled with non-combustible materials such as mica, or talc clay, lime, and graphite. Asbestos commenced to be used about the same time.

The great fire in New York City in 1835, destroying hundreds of millions of dollars' worth of property of every description, gave a great impetus to the invention of fire-proof safes in America.

B. G. Wilder there patented in 1843 his celebrated safe, now extensively used throughout the world. It consisted of a double box of wrought-iron plates strengthened at the edges with bar iron, with a bar across the middle; and as a filling for the inters.p.a.ces he used hydrated gypsum, hydraulic cement, plaster of paris, steat.i.te, alum, and the dried residuum of soda water.

Herring was another American who invented celebrated safes, made with a boiler-iron exterior, a hardened steel inner safe, with the interior filled with a casting of franklinite around rods of soft steel. Thus the earth, air and water were ransacked for lining materials, in some cases more for the purpose of obtaining a patent than to accomplish any real advance in the art. Water itself was introduced as a lining, made to flow through the safes, sometimes from the city mains, and so retained that when the temperature in case of fire reached 212 F. it became steam; and an arrangement for introducing steam in place of water was contrived. Among other lining materials found suitable were soapstone, alumina, ammonia, copperas, starch, Epsom salts, and gypsum, paper, pulp, and alum, and a mixture of various other materials.

After safes were produced that would come out of fiery furnaces where they had been buried for days without even the smell of fire or smoke upon their contents, inventors commenced to direct their attention to burglar-proof safes.

Chubb, in 1835, patented a process of rendering wooden safes burglar proof by lining them with steel, or case-hardened iron plate. Newton in 1853 produced one made of an outer sh.e.l.l of cast iron, an interior network of wrought iron rods, and fluid iron poured between these, so that a compound ma.s.s was formed of different degrees of resistance to turn aside the burglar's tools. Chubb again, in 1857, and in subsequent years, and Chartwood, Glocker, and Thompson and Tann and others in England invented new forms to prevent the insertion of wedges and the drilling by tools. Hall and Marvin of the United States also invented safes for the same purpose. Hall had thick steel plates dovetailed together; and angle irons tenoned at the corners. Marvin's safe was globeshaped, to present no salient points for the action of tools, made of chrome steel, mounted in this shape on a platform, or enclosed in a fire-proof safe. Herring also invented a safe in which he hinged and grooved the doors with double casings, and which he hung with a lever-hinge, provided the doors with separate locks and packed all the joints with rubber to prevent the operation of the air pump--which had become a dangerous device of burglars with which to introduce explosives to blow open the doors.

Still later and more elaborate means have been used to frustrate the burglars. Electricity has been converted into an automatic warder to guard the castle and the safe and to give an alarm to convenient stations when the locks or doors are meddled with and the proper manipulation not used. Express safes for railroad cars have been made of parts telescoped or crowded together by hydraulic power, requiring heavy machinery for locking and unlocking, and this machinery is located in machine shops along the route and not accessible to burglars.

About 1815 inventors commenced to produce devices to show with certainty if a lock had been tampered with. The keyhole was closed by a revolving metallic curtain, and paper was secured over the keyhole. As a further means of detection photographs of some irregular object are made, one of which is placed over the keyhole and the other is retained. This prevents the subst.i.tution of one piece of paper for another piece without detection. A large number of patents have been taken out on gla.s.s coverings for locks which have to be broken before the lock can be turned. These are called seal locks.

Locks of various kinds, consisting at least of the two general features of a bolt and a key to move the bolt, have existed from very ancient days. The Egyptians, the Hebrews and the Chinese, and Oriental nations generally had locks and keys of ponderous size. Isaiah speaks of the key of the house of David; and Homer writes sonorously of the lock in the house of Penelope with its brazen key, the respondent wards, the flying bars and valves which,