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History of the Microscope
THE
VETERINARY JOURNAL AND
~nnals
of
HISTORY OF THE MICROSCOPE. BY PROFESSOR O. C. BRADLEY, NE\V VETERINARY COLLEGE, EDINBURGH.
THE microscope is daily being more and more pressed into the service of the scientist, to enable him to elucidate the problems met with in everyday life, and the veterinarian has not been behind in accepting to the full the great advantages accruing from the use of this wonderful and exceedingly useful instrument. The diseased condition of animals which up to comparatively recent times were mysteries and treated as such, are now, comparatively speaking, an open book to us, thanks to the untiring energy and industry of the microscopist. Diseases which, in the days of our forefathers, were put down to " humours" and other occult and mythical things, we now know to be due to vital processes brought about by specific and non-specific causes; it is within recent years that those scourges of the animal kingdom, viz., contagious diseases, have been proved to be due to specific causes. If the dead and gone pathologist of say fifty years ago could only re-visit this earth, he would indeed be greatly surprised at the rapid and almost incredible stride his particular science has made, and much, nay, we may almost say most, of the advance of pathological and allied science has been due to improvement in the mechanical and optical parts of the microscope; certainly no other instrument can be said to have done so much to forward the healing art. Surprising though the progress of the last fifty years has been, what may it not be in the next half-century? We now know that animals are preyed upon by m~croscopic plants and animals, shall We next be told that these in their turn VOL. XXXVnL
Q
234
The Vetertl1ary Journal.
are infested by parasites? Who can tell? Perhaps the wellknown couplet that : "Big fle as have little fleas upon their back to bite 'em, And little fl eas have lesser fleas and so ad infinitum,"
will ultimately be found true to the letter. Anyhow, we have no r eason to be otherwise than satisfied with the progress achieved hitherto, and without doubt the future, through the medium of the microscope, has equally great wonders to unfold. The microscope at its birth was not put to any serious uses, but was m erely a toy, and contributed to the amu sement of the dt'letta12tt~ who little dreamed that the insignificant plaything would in the course of time place humanity under such a debt as it has. The early history of Optics is very obscure and uncertain. for though we are told that the Egyptians, Chaldeans, and Chinese were keen astronomers, we do not know, with certainty, that they employed instruments at all like tel escopes j indeed, records point to the fact that they were ig norant of the most elementary laws of optics, for thoug h they used burning glasses, they probably did so without knowing much of the theory of their action. Aristophanes, in 43 r B .C., mentions burning glasses, and we read of the Rom an fl eet in 250 B.C., being set fire to at Syracuse, by the sun's rays, concentrated by means of specula of polished metal. The British Museum authorities have in their possession a very interesting piece of rock-crystal, known as the "Assyrian lens," which is plano-convex, oval in shape, and appears to have been ground, and at least partially polished. It is on the authority of Sir James Brewster that it is called a "lens." The approximate date of its manufacture has been fixed at between 7 2 I and 705 B.C., but whether it was u ~ed for magnifying purposes or not, is open to question. About 50 A.D., Seneca discovered that hollow g lass spheres filled with water h ad a magnifying power. Ptolemy, about 140 A.D., seems to have been the first to seriously study the laws of light. After the discovery of the magnifying power of globes of water, little seems to have b een done until the I rth century, when the subj ect was apparently revived. The name of Friar Roger Bacon, is connected with the invention of spectacles in the t3th century, and this is probably the first serious use to which magnifying glasses were put j and it is to a spectacle. maker of Holland that the name of the "Father of the microscope," is applied.
History
of the
M£croscope.
235
The first simple microscope consisted of a cylindrical box' having a lens fixed to the top, and two pieces of glass at the bottom, between which the object to be viewed was fixed. This microscope derived its name "vitrum pulicorium," from the obj ect usually b eing a flea, which, no doubt, was con sidered to be a very wonderful and hig hly interesting s ig ht. Leeuwenhock, the illustrious microscopist and originator of b acteriology, constructed an instrument in which th e lens was fixed in a metal plate, and underneath was a needle on the point of which the obj ect . to b e examined wa s impaled; the needle could be raised or lowered at will by means of a screw. Hooke, in 1665, seems to have been the first to use lenses of cast g lass; up to hi s time cut lenses were the only kind e mployed. \Vilson, about 1740, considerably improved the s imple microscope by mountin g it on a foot a nd supplyin g it with a hin ged mirror; thi s being furth er improved by Cuff, in 1750, who, making the stage moveable, g ave u s the ty pe of th e present d ay :si mple m icroscope. T he co mpound m icroscope w as invented by Za cch ari as J anssen, a sp ectacle m ak er a nd optician, livin g in Middleburg. Holland. Most have h eard the story of how one day h e h appen ed to hold two spectacle len ses one above the other a nd found tha t the magnification was g reater than wh en only o ne len s w as used. H e immediately set about m aking an inst rument consisting of four tubes sliding within each other, two of which carri ed lenses. It was n ecessary to h old this instrum ent up t o th e lig ht, as no mirror . was u sed. The above discovery h as been claimed for the Italian Galileo, but th oug h he certa inly m ade a microscop e, it is proved th a t it was not in any way like J anssen's. It is interesting to note tha t so me of the early co mpound microscopes we re m ad e of such large dimen sion s th at the tube is said to h ave been as thi ck a s a man's leg. a nd th e eye-piece the size of th e palm of th e hand. H ook e m a de a compound microscope about J 665 which was mounted on a foot a nd h ad the tube inclinable, but the object could only b e examin ed by lig ht thrown upon it from above. The lig ht w as concentrated by interposin g a g lass g lobe b etwee n the obj ect and a lamp; this seem s to h ave been th e first attempt a t m akin g a conde nser. A tru e condenser was used by R eve Bouanni ab out 169 I, an d, in fact, h is instrum ent was the ge rm from which the m od p.rn micro-
23 6
The Vetert"nary journal.
scope has sprung; it was horizontal, and had both rapid and slow movements. An inclinable microscope was made by John Marshall, of London, in 1704, in which six objectives could be used, magnifying from 4 to 100 diameters. In 1744, Cuff made the stage free, and so that a diaphragm could be fitted underneath. Martin made his Large Universal Microscope about 1780. Up to the present century prog ress had b een slow and spasmodic, but after the introduction of achromatism, in 1824 or 1830, a change took place, and rapid progress was made: in fact, the history of the microscope may be divided into , ancient and modern-ancient b efore 1830, modern after that date. The names of Van Deyl, Vincent, Cheva.lier, and Amici are found associated with mechanical and optical improvements in recent years. The binocular or stereoscopic microscope was warmly advocated by Carpenter, and not without good r eason, for by it was demonstrated" the value of the conjoint use of both eyes in conveying to the mind a notion of the solid form of objects, such as the use of either eye singly does not generate with like certainty or effectiveness." The introduction of "Immersion " systems we may consider the latest great advance made. Amici long ago pointed out the fact that a drop of water introduced b etween the cover glass and the front of the objective diminished the loss of light resulting from the passage of the rays from the object into air, and then from air into the object glass; and recently Abbe (among others), has r eplaced the drop of water by one of cedar oil, which he found to have nearly the same refractive and di spersive power as crown glass. Still more recently, Zeirs, of J en a, has introduced a more perfect immersion lens, but as its price is £ 40 it is not likely to come into general use. When the necessity arose for m aking a permanent record of the image seen through ' the microscope, numerous instruments were made to facilitate drawing. There are in present use various forms of camera lucida, but none are without some drawback. Mr. Forgan, of this city, has made an instrument which projects the image on to the drawingpaper, and so drawing is made easy, but this little accessory can only be used with comparatively low power. Photography has b een pressed into the service of the microscopist, and is now in very g eneral use, in fact, one now sees very few papers in the scientific journals, which are not
Single Molar Tooth Rasps.
~37
illustrated by photo-micographs. Should photography of colours ever b ecome an established fact, no science or art will derive more b enefit from it than microscopy. Such, then, is a very imperfect account of the history of a universally employed instrument. W e have seen from whence it came, a nd what it has become j what it will b e, no one can tell, and I cannot end b etter than by quoting Professor Abbe's words :-" I believe that those instruments, which may, perhaps, in the future, more effectively aid our sen ses in the investigation of the ultimate elements of the m ateria l world than the microscope of the present, will have little else than the nam e in common with it."
SINGLE MOLAR TOOTH RASPS. BY VE TERI NAR Y-MAJOR 1. MATTH EWS, F .R .C. V.S., F . R.G.S., AR:llY REM OUNT S T AFF, D UB LI N.
THE gr eat amount of care now d evoted to minor everyday operation s in Equine D ental Surgery has produced a variety
f7xa ~~~~====~of rasp s calculated for use on single mola rs, as opposed to the "old time" sy ste m of wholesale reduction by six and eig ht-in ch rasps . Those I now wish to place before the profession h ave been constructed with considerable care by Messr s. Arnold & S ons, whom I have to thank for the minute attention they h ave bestowed on their construction, and they are th e on es I recommend to be used in my Paper on Dentistry in th e 4th edition of Sir F. Fitzwygram's "Horses and Stables." Their a dvantages may be enumerated as follows : 1st. T he lightness of the " business," or operatin g end, r eadily allows of their use with one hand. 2nd. Their "lateral guards " offer sufficient guarantee against injury to the buccal membra ne, and assist t o r etain the rasp surface on the tooth operated on, difficulties I have more than once encountere d in operating with somewhat simila r rasps without them. 3 r d. The three rasp heads vary in their curves, in view of more r eady adjustme nt to varying conditions of abnormal g rowth.
VETERINARY JOURNAL AND
~nnals
of
HISTORY OF THE MICROSCOPE. BY PROFESSOR O. C. BRADLEY, NE\V VETERINARY COLLEGE, EDINBURGH.
THE microscope is daily being more and more pressed into the service of the scientist, to enable him to elucidate the problems met with in everyday life, and the veterinarian has not been behind in accepting to the full the great advantages accruing from the use of this wonderful and exceedingly useful instrument. The diseased condition of animals which up to comparatively recent times were mysteries and treated as such, are now, comparatively speaking, an open book to us, thanks to the untiring energy and industry of the microscopist. Diseases which, in the days of our forefathers, were put down to " humours" and other occult and mythical things, we now know to be due to vital processes brought about by specific and non-specific causes; it is within recent years that those scourges of the animal kingdom, viz., contagious diseases, have been proved to be due to specific causes. If the dead and gone pathologist of say fifty years ago could only re-visit this earth, he would indeed be greatly surprised at the rapid and almost incredible stride his particular science has made, and much, nay, we may almost say most, of the advance of pathological and allied science has been due to improvement in the mechanical and optical parts of the microscope; certainly no other instrument can be said to have done so much to forward the healing art. Surprising though the progress of the last fifty years has been, what may it not be in the next half-century? We now know that animals are preyed upon by m~croscopic plants and animals, shall We next be told that these in their turn VOL. XXXVnL
Q
234
The Vetertl1ary Journal.
are infested by parasites? Who can tell? Perhaps the wellknown couplet that : "Big fle as have little fleas upon their back to bite 'em, And little fl eas have lesser fleas and so ad infinitum,"
will ultimately be found true to the letter. Anyhow, we have no r eason to be otherwise than satisfied with the progress achieved hitherto, and without doubt the future, through the medium of the microscope, has equally great wonders to unfold. The microscope at its birth was not put to any serious uses, but was m erely a toy, and contributed to the amu sement of the dt'letta12tt~ who little dreamed that the insignificant plaything would in the course of time place humanity under such a debt as it has. The early history of Optics is very obscure and uncertain. for though we are told that the Egyptians, Chaldeans, and Chinese were keen astronomers, we do not know, with certainty, that they employed instruments at all like tel escopes j indeed, records point to the fact that they were ig norant of the most elementary laws of optics, for thoug h they used burning glasses, they probably did so without knowing much of the theory of their action. Aristophanes, in 43 r B .C., mentions burning glasses, and we read of the Rom an fl eet in 250 B.C., being set fire to at Syracuse, by the sun's rays, concentrated by means of specula of polished metal. The British Museum authorities have in their possession a very interesting piece of rock-crystal, known as the "Assyrian lens," which is plano-convex, oval in shape, and appears to have been ground, and at least partially polished. It is on the authority of Sir James Brewster that it is called a "lens." The approximate date of its manufacture has been fixed at between 7 2 I and 705 B.C., but whether it was u ~ed for magnifying purposes or not, is open to question. About 50 A.D., Seneca discovered that hollow g lass spheres filled with water h ad a magnifying power. Ptolemy, about 140 A.D., seems to have been the first to seriously study the laws of light. After the discovery of the magnifying power of globes of water, little seems to have b een done until the I rth century, when the subj ect was apparently revived. The name of Friar Roger Bacon, is connected with the invention of spectacles in the t3th century, and this is probably the first serious use to which magnifying glasses were put j and it is to a spectacle. maker of Holland that the name of the "Father of the microscope," is applied.
History
of the
M£croscope.
235
The first simple microscope consisted of a cylindrical box' having a lens fixed to the top, and two pieces of glass at the bottom, between which the object to be viewed was fixed. This microscope derived its name "vitrum pulicorium," from the obj ect usually b eing a flea, which, no doubt, was con sidered to be a very wonderful and hig hly interesting s ig ht. Leeuwenhock, the illustrious microscopist and originator of b acteriology, constructed an instrument in which th e lens was fixed in a metal plate, and underneath was a needle on the point of which the obj ect . to b e examined wa s impaled; the needle could be raised or lowered at will by means of a screw. Hooke, in 1665, seems to have been the first to use lenses of cast g lass; up to hi s time cut lenses were the only kind e mployed. \Vilson, about 1740, considerably improved the s imple microscope by mountin g it on a foot a nd supplyin g it with a hin ged mirror; thi s being furth er improved by Cuff, in 1750, who, making the stage moveable, g ave u s the ty pe of th e present d ay :si mple m icroscope. T he co mpound m icroscope w as invented by Za cch ari as J anssen, a sp ectacle m ak er a nd optician, livin g in Middleburg. Holland. Most have h eard the story of how one day h e h appen ed to hold two spectacle len ses one above the other a nd found tha t the magnification was g reater than wh en only o ne len s w as used. H e immediately set about m aking an inst rument consisting of four tubes sliding within each other, two of which carri ed lenses. It was n ecessary to h old this instrum ent up t o th e lig ht, as no mirror . was u sed. The above discovery h as been claimed for the Italian Galileo, but th oug h he certa inly m ade a microscop e, it is proved th a t it was not in any way like J anssen's. It is interesting to note tha t so me of the early co mpound microscopes we re m ad e of such large dimen sion s th at the tube is said to h ave been as thi ck a s a man's leg. a nd th e eye-piece the size of th e palm of th e hand. H ook e m a de a compound microscope about J 665 which was mounted on a foot a nd h ad the tube inclinable, but the object could only b e examin ed by lig ht thrown upon it from above. The lig ht w as concentrated by interposin g a g lass g lobe b etwee n the obj ect and a lamp; this seem s to h ave been th e first attempt a t m akin g a conde nser. A tru e condenser was used by R eve Bouanni ab out 169 I, an d, in fact, h is instrum ent was the ge rm from which the m od p.rn micro-
23 6
The Vetert"nary journal.
scope has sprung; it was horizontal, and had both rapid and slow movements. An inclinable microscope was made by John Marshall, of London, in 1704, in which six objectives could be used, magnifying from 4 to 100 diameters. In 1744, Cuff made the stage free, and so that a diaphragm could be fitted underneath. Martin made his Large Universal Microscope about 1780. Up to the present century prog ress had b een slow and spasmodic, but after the introduction of achromatism, in 1824 or 1830, a change took place, and rapid progress was made: in fact, the history of the microscope may be divided into , ancient and modern-ancient b efore 1830, modern after that date. The names of Van Deyl, Vincent, Cheva.lier, and Amici are found associated with mechanical and optical improvements in recent years. The binocular or stereoscopic microscope was warmly advocated by Carpenter, and not without good r eason, for by it was demonstrated" the value of the conjoint use of both eyes in conveying to the mind a notion of the solid form of objects, such as the use of either eye singly does not generate with like certainty or effectiveness." The introduction of "Immersion " systems we may consider the latest great advance made. Amici long ago pointed out the fact that a drop of water introduced b etween the cover glass and the front of the objective diminished the loss of light resulting from the passage of the rays from the object into air, and then from air into the object glass; and recently Abbe (among others), has r eplaced the drop of water by one of cedar oil, which he found to have nearly the same refractive and di spersive power as crown glass. Still more recently, Zeirs, of J en a, has introduced a more perfect immersion lens, but as its price is £ 40 it is not likely to come into general use. When the necessity arose for m aking a permanent record of the image seen through ' the microscope, numerous instruments were made to facilitate drawing. There are in present use various forms of camera lucida, but none are without some drawback. Mr. Forgan, of this city, has made an instrument which projects the image on to the drawingpaper, and so drawing is made easy, but this little accessory can only be used with comparatively low power. Photography has b een pressed into the service of the microscopist, and is now in very g eneral use, in fact, one now sees very few papers in the scientific journals, which are not
Single Molar Tooth Rasps.
~37
illustrated by photo-micographs. Should photography of colours ever b ecome an established fact, no science or art will derive more b enefit from it than microscopy. Such, then, is a very imperfect account of the history of a universally employed instrument. W e have seen from whence it came, a nd what it has become j what it will b e, no one can tell, and I cannot end b etter than by quoting Professor Abbe's words :-" I believe that those instruments, which may, perhaps, in the future, more effectively aid our sen ses in the investigation of the ultimate elements of the m ateria l world than the microscope of the present, will have little else than the nam e in common with it."
SINGLE MOLAR TOOTH RASPS. BY VE TERI NAR Y-MAJOR 1. MATTH EWS, F .R .C. V.S., F . R.G.S., AR:llY REM OUNT S T AFF, D UB LI N.
THE gr eat amount of care now d evoted to minor everyday operation s in Equine D ental Surgery has produced a variety
f7xa ~~~~====~of rasp s calculated for use on single mola rs, as opposed to the "old time" sy ste m of wholesale reduction by six and eig ht-in ch rasps . Those I now wish to place before the profession h ave been constructed with considerable care by Messr s. Arnold & S ons, whom I have to thank for the minute attention they h ave bestowed on their construction, and they are th e on es I recommend to be used in my Paper on Dentistry in th e 4th edition of Sir F. Fitzwygram's "Horses and Stables." Their a dvantages may be enumerated as follows : 1st. T he lightness of the " business," or operatin g end, r eadily allows of their use with one hand. 2nd. Their "lateral guards " offer sufficient guarantee against injury to the buccal membra ne, and assist t o r etain the rasp surface on the tooth operated on, difficulties I have more than once encountere d in operating with somewhat simila r rasps without them. 3 r d. The three rasp heads vary in their curves, in view of more r eady adjustme nt to varying conditions of abnormal g rowth.