Spencer Buffalo Model 44, Construction, Use And Care

Page 1: ...F li 1I I i l I TF tE NITXCROSCOPE CONSTRUCTION USE AND CARE PUBLISHED BY SPENCER LENS COMPANY BIJFFALO N Y ...

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Page 3: ... CONSTRUCTION USE AND CARE of the MICROSCOPE A brief outline of the mechanical and optical principles involved with special referencc to efficient manipulation PUBLISHED BY SPENCER LENS COMPANY BUFFALO N Y ...

Page 4: ...ruction the care and the use of the instrument both mechanical and optical going into detail only in so far as is necessary to make the instrument an efficient means for the study of the subject at hand Let it be remembered that no amount of direction will take the place of good judgment and careful painstaking effort on your part and that it is only the perfect adjustment of every part in relatio...

Page 5: ...wTqbe Bod2 lube Dre Tube Draph agn with Socie r Sc w Socie 5cren lr roscope rs reg ularly sent out fromthe VERYmic factory securely packed in a case which becomes a safe abiding place for the in strument when not in use After using it should always be re turned to its Case or protect ed in some other way from dirt and dust and from direct sun light The case is always a safe vehicle for car rying t...

Page 6: ...ined to any angle which ease and con venie nce may dictate The joint should work smoothly and freely and yet with sufficient friction to hold thL body at any inclination There are several types of construction as illustrated fn all of them the pil ar forms two parts of the hinge while the lowcr end of the arm is made to fit betwee n In all the best types the taper axle or a modification I is predo...

Page 7: ...he fine adjustment up and down while the eye is at the eyepiece the object appears to move sidewise the light coming from the mirror is not central or there is a lateral movement in the fine adjustmcnt bcarings If upon carefully centering the light the rpparent movement of the object per sists the trouble is in the fine adjustment either poor fitting a decided lateral thrust in the mechanism pro d...

Page 8: ...one on either side of the arm I he mechanism here is slightly more complicated hence the need for the best mechani cal principles The bearings for the shaft connecting the two heads are on cither sidc of the arm and should be in precise alignment for the free turning of the shaft In no way is this accomplished as well as where the two bearings are in one continuous piece passing through the arm He...

Page 9: ...ard microscopes are now made so that the positive impulse is always upward l4 against a slightly compressed spring The mechanism allows the movable parts to descend by gravity and the force of the compression spring Therefore in focus sing down one is not so apt to cause damage if the front of the objective should come into contact with the cover glass Avoid this contact if possible If at all unce...

Page 10: ...f place and the other replaced without the least danger of disturbing the focus of the highest power objectives Asillustratedonnextpage the light from the objective is divided by two cemented prisms immediately above 16 tr is K the objective The 45o surface of one of these prisms is semi platinized to reflect half the light to one side and allow the other half to pass through to be reflected in th...

Page 11: ... so brilliant a field with thc sarne light source Many therefore considcr thc singlc eyepiece better when a brighter field is dcrnaudcd and when the exigencies require the most cirilical definition and resolution Without doulrt thc two views of the same object are different antl both rnake for a more intelligent inter pretation l lren fort rnosl workers are willing to use both tubes cverr though t...

Page 12: ...e it can be cleaned with a little xylol or 90 chloroform If this has a tendency to turn the stage gray rub on a little heavy oil to restore the original black If the gray color is of long standing let the oil remain for a time always wiping ofi before using the microscope All stages are either rectangular or circular The rectan gular are used in the great proportion of laboratory work because of t...

Page 13: ... do not start back easily Try starting them in a new place Remember there are 22 six threads each working best in its own thread in the nut If the leaves of the iris diaphragms become rusted or gummed clean them with xylol and oil them thoroughly by opening and closing the diaphragm several times to evenly distribute the oil over the leaves Should the leaves become bent or misplaced submit them to...

Page 14: ...or is properly adjusted the focussing of the condenser does not interfere with the direction of the light 24 PART II General Theory of Microscope oji Ray Paths Axial Rays A IIICROSCOPB objective a forms an image that may be a con idered as made up of an infinite number of points A study of two of these points will give a good idea of how thc objective functions to forrn tlris image l he first poin...

Page 15: ...me plane The eye lens of the eyepiece deviates the principal ray so that it crosses the axis at the point R D which is variously called the Ramsden disc exit pupil or eyepoint ft is the point at which the pupil of the eye should be placed to be able to see the whole field The other rays of the bundle surrounding the principal ray are made parallel to it by the eye lens if the microscope is correct...

Page 16: ...ve alone by 10 the magnification of the eyepiece 8A Defi nition Spherical Aberration In explaining the paths of rays through a microscope objective it was assumed that the rays crossed at a point to form an image This is never strictly true and is approximated only when the correction for spherical aberration is good If the correction for spherical aber ration is perfect the rays of a bundle are s...

Page 17: ...ely pleasing to the eye in its crispness of detail and faithfulness of reproduction of color 30 Resolving Power What It Is There is a conception among some users of the micro scope that magnification and definition are of para mount importance This is not strictly true for there is another requirement that is more important than either of these This is resolving power the ability to pick out and r...

Page 18: ...he oil This is only true howevei if a condenser of at least the same numerical aperture as the objective is used and if an oil contact is used between the condenser and the sl ide Necessity of Immersing Condenser Figure S shows the top lens of a condenser and the front S pug 3 aa Iens of an oil immersion objective with the slide and cover glass between The ray marked p p is shown traversing the sy...

Page 19: ...he reason why the quantity n enters into the expres sion for numerical aperture again involves the fact that light is a wave motion When the rays forming a wide angle cone impinge on an object they are jostled by a process called diffraction into groups with a separation between them The sum total of these groups lies in a cone of larger angle than the original illumi nating cone In other words th...

Page 20: ...trrrscr is used This ernphasizes the necessity of rrsirrg ir r ondenser when high resolving power is rtxluit t rl l lris limit of resolution is not dependcnt on thc Irr r g nilication providing sufficient magnification is uscd I irr irrst llnce no amount of magnification will show l lrrr scparation between two objects that are separated by X 0f mm unless an objective of at least 95 numeri ill tper...

Page 21: ...lessened thereby PART III The Use of the Microscope Equipment A MICROSCOPE equipment may be very elabo rate and some rvork requires such an outfit but ever v rnicroscope to be e ficient should be pro virlcd with at least tw o objectives and preferably two x ulars If but one ocular is bought the 10X or l is lrest If two are provided the 6X and 10X 2 and 1 rre preferable For ordinary biological hist...

Page 22: ...orities claim that the light from the blue 40 sli1 is best Avoid the use of direct sunlight If the room is so situated that the sun shines in use white shades Lo rnodify the light If possible select a rvindow which is frcc from cross bars wire nettings etc and which is surne distance from swaying branches of trees lfor long continued work on any one subject artificial liglrt has one advantage over...

Page 23: ...o ilrove in the direction opposite to that in which it is moved This along with the fact that the microscope 42 rrrl gnifies the movement as rvell as the specimen is perplexing at first and makes it difficult to move the spcr irnen just where it is wanted and no farther With pnrctise comes the delicacy of movement which enables orrc to put the specimen iust where he wants l lrc beginner should ah ...

Page 24: ...inltself doei not insure axial 44 liglrt I he mirror must be so turned that the rays of light or the axis of the cone of light reflected from it crrtcr the objective parallel to its axis This can not rrlwa ys be done Other considerations are more impor l tnt than exact central light In working with daylight rcflcctions from trees window sash etc are apt to bc seen on the mirror If the whole micros...

Page 25: ...t the back of the ob ieetive is fullv and evenlv illrrrninaled and jI possible free from uny i ug s df llccs window sashes ctc If these images can not be lispelled by turning the mirror use the orr ave mirror S lightly lowe_ring the condenser will also accomplish the same end but there is an objection to doing this ttnless it is necessar t The condenser does its besiwork txrlv rvhen the source of ...

Page 26: ...en a condenscr is used The tt1 t of the orrr should be carefully centered in i 8 llrc lrack of the objective by twisting the mirror after llro rnirror bar has been swung to the median line If llrr source of light is a ground glass or Daylite glass rr s is the case in most of the lamps especially designed I or rnicroscope illumination this glass should be so placcd that a line perpendicular to the ...

Page 27: ...best of them r u light source built into them sothattheadjustment of ttr tigit which is always troublesome is made easier 50 The Objectives In IJse Cleaning the Objectives l o get the best results with a microscope objective it is absolutely necessary that it should be clean The pt rformance of a high power objective can be ruined lry clirt of any kind especially on the surface nearest llrc cover ...

Page 28: ... is best to wipe all oil from the objective ar d co rir glass and start over The necessity of im ti g thE condenser when using an oil immersion 52 olricctive l ras already been dealt with at length It rrrly not be amiss however to mention it again Tube Length and Cover Glass All objectives are corrected to a certain tube length l iOmm by most makers Leitz l70mm and all ob ir tives in fixed mounts ...

Page 29: ...spherical aber ration is poorly corrected these edges will be bordered 54 by a fringe of turbid grey as well as the usual color fringe when oblique light is used A ge neral haziness that causes a washed out appearance to the j ug9 ulder all conditions is almoit always caused by dirt It is easy to locate by removing tLe cycpiece and looking through the back of the objeJtive rnd must be removed befo...

Page 30: ...eyepiece Sometimes dirt on the lenses of the condenser will cause spots in co t ire field that closely resemble those caused by dirr in the eyepiece Final Hints Somctimes the rn orker mav have faithfully carried out tll the directions heretofore given and been assured tlrat his lenses possess the abor e named qualities as thev ought yet be unable to obtain the desiied results llc may be working wi...

Page 31: ...tained by moving the slide about to bring different parts into the optical axis and by focussing with the fine adjustment to bring different levels or optical planes successively into view Where serial sections are used each section must be studied in relation to its neighbors Sometimes sections which are freshly mounted in bal sam appear cloudy and indistinct This is because of failure to thoroug...

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