![](/uploads/1/2/7/1/127194343/319845767.jpg)
Up to 1942 Bausch & Lomb, Rochester USA used a numerical. Letter is significant for the production date, the second is a code class for lenses, microscopes etc. So to be complete, here the serial numbers before 1942.
The history of the of Rochester N.Y. And itsearly association with the innovativemicroscope maker and designer has already been well-documented 1, 2, 3 and will notbe repeated here in detail. Starting fromabout 1876, and throughout the century,the Bausch & Lomb Optical Companyproduced a number of microscopes ofdifferent designs. The earlier models werefrequently given names. Among these werethe Library, Family, Student, Educational,Research, Laboratory, Physician’s, Model,Harvard, Investigator, Universal,Concentric, University, and Professionalmodels.
4 Over the course of thecentury many of these models evolved asthey incorporated new ideas. The purposeof this essay is to describe the evolutionof one of these models, the top of theline, the Professional model.The earliest version of the B& LProfessional microscope, as designed byErnst Gundlach, first appeared in1876-1877. An example of one of theseinstruments is shown in figure 1. Themicroscope is signed on the tube “Bausch& Lomb Optical Co., Rochester NY” andon one of the plates covering the fineadjustment mechanism appears the patentdate Oct. 3, 1876 corresponding to. The serial number,which is stamped onto the bottom of thecase, is 76.
The microscope is constructedlargely of brass and measures about 17inches tall as shown in the photograph.Rising from the novel and oddly shapedbase are two turned pillars that supportthe body of the microscope. Tension forthe inclination of the microscope can beadjusted using brass knobs located oneither side of the axis of inclination.The stage of the microscope consists of abrass frame and an attached thick glassplate with a 3/4 inch opening. Mounted onthe plate is the nickel-plated slidingslide holder with hard rubber knobs. Theslide holder can be detached and two stageclips that are among the accessories ofthe microscope can be substituted for it. The mirror is double-sided with the framemade of hard rubber and it is attached toa swinging arm. The mirror can be focusedby sliding along the arm.
Also attached to the arm is the substage apparatus holderthat mounts various accessories. The substage holder is connected to the armvia a dovetail fitting that allows for itsquick removal and insertion. In additionto being capable of utilizing aconventional condenser, the microscope isset up for use of immersion condensers.Two of these, one for high and the otherfor low power work were supplied with themicroscope. They mount directly under theglass stage using a bayonet-mountingbracket.
The microscope has a Jackson limbwith coarse focusing by rack and pinion.Fine focusing is acheived by using amicrometer screw located behind the tube.It utilizes Gundlach's new ' frictionless'fine adjustment mechanism that isdescribed in the 1876 patent. The tubelength can be extended by means of adrawtube.
The drawtube is nickel-platedand is terminated with a Society screw foruse with an accessory apparatus such asthe analyzer prism or for use with verylow power objectives. The microscope wasfound with its walnut case and a number ofaccessories. These include:Three eyepieces in hard rubber mounts labeled ' B', ' C', and ' D' The ' D' is marked ' E.
Gundlach Periscopic' and is slotted for a micrometer.Three objectives among which are a 2-inch and a 3/4-inch, each signed E. The 2-inch is mounted in hard rubber and both have hard rubber canisters. The third objective is a W.
With the microscope just described, themovement of the mirror bar is restrictedto angles below the stage, but accordingto a 1879 catalog 6, amodification was made to the modelprimarily involving the mirror bar. It isstated in the catalog“ Themirror may be brought to any obliquity andswung above the stage for illumination ofopaque objects. The mirror, as well as,the substage, can be moved on the mirrorbar to and from the object, and both canbe removed altogether, in an improvedmanner not shown in the illustration”.In addition, the glass stage with slideholder is now“ circularin form”.
I have not been able tolocate an example or illustration of theProfessional of 1879 showing theseimprovements. It is not clear how many ofthese modified Professionals were actuallyproduced since during this transitionperiod, the model was a work in progress.No Professional microscope was offered inthe 1880 Bausch & Lombcatalog 7, perhaps because thedesign of a new model was in a state offlux. One likely impetus for redesigningthe Professional model was the progressbeing made by the competition.
Compared toor models, both introduced about thesame time as the Professional, the Professionalalready appeared old fashioned. It was notcapable of utilizing the emerging ideasconcerning extreme oblique illumination.The new Professional was designed tocorrect this.The new Professional became available by1883. The microscope was completelyredesigned producing, essentially, adifferent instrument.
An example of one ofthese with a binocular tube is shown infigure2.The microscope is signed on the base“Bausch & Lomb Optical Co., RochesterNY”and again it bears thepatent date. Laterversions of this microscope also have anpatent date. Curiously,neither the microscope nor its case ismarked with a serial number. The lackof the 1885 patent date might suggest thatthis instrument was made prior to 1886,but without a serial number, this isuncertain.
The base is now a tripod with abronze-like finish. Attached to the tripodand the two turned pillars is a circularplate with a calibrated silvered scale onwhich the entire instrument can rotate.The purpose of this feature, firstintroduced by Joseph Zentmayer in the, was to allowmeasurement of the angular aperture ofobjectives. As with the earlierProfessional, the tension for inclinationof the microscope can be adjusted usingbrass knobs located on either side of thetrunnions. The substage of this versionhas been completely redesigned andupgraded. The double mirror and substage are mountedon independent arms, both of which arecapable of being oriented in any positionincluding above the stage (see figure 3).Calibrated silvered scales measure angularof movement of each arm. The movements ofthe substage components were designed sothat the axis of rotation of the arms arein the plane of the specimen, thusensuring that the illumination is alwaysin focus.
This elaborate arrangement wasdesigned to allow any degree of obliqueillumination including illumination ofopaque objects from above. Earlier, inAmerica, Tolles, Zentmayer, and Bullochincorporated similar arrangements on someof their stands. These refinements werealso incorporated by a number of Europeanmakers. The mirror can be independentlyfocused by sliding on its arm and thesubstage holder, with centeringadjustments, is focused using a rack andpinion.The stage on the microscope is of theTurrell form with milled control knobsplaced one above the other (see figure 4).This arrangement allows complete rotationof the stage. This model is most often found suppliedwith a monocular tube with drawtube. Theexample presented here is exceptional inthat it was furnished both with binocularand petrological tubes.
As with theearlier Professional, the Jackson limb isretained. Coarse focusing of the tube isby rack and pinion and the internalcomponents of the fine focusing mechanismare similar to those used in the earliermodel. One modification of the fineadjustment found on this example is theincorporation of a differential screw (seefigure 5). According to the1892 B& L catalog, 8when thethumb screw located at the top of the fineadjustment knob is free, the mechanismfunctions as a conventional one with onerevolution of the knob moving the tube1/75 inch. When the thumbscrew istightened, the differential effect comesinto play and one revolution of the knobmoves the tube 1/300 inch.This slowermovement is useful when using highmagnification. The differential screwarrangement was optional and not all theProfessionals are equipped with thisfeature.
9 The interocular separation of thebinocular tubes is controlled by rack andpinion. The binocular arrangement on thismicroscope incorporates what is claimed tobe a novel mounting of the Wenham prism. It is described in a patentgranted to Edward Bausch(, Feb. Theconventional mounting of a Wenham prismutilizes a brass box that slides laterallyinto the lower portion of the tube. Withthis new arrangement, the prism is mountedon a spindle extending through a sleevepassing through the front of the tube. Themilled head of the spindle is turned torotate the prism in and out of the opticalpath. The stated advantages of this newarrangement are that it negates anydefects that might be present on thebearings of the box type of mounting andthat it allows the use of a larger prismwhich is an advantage when using highangle objectives.
10Figure 6 shows the microscope set up withthe petrological tube in place. The tubeincorporates a Nicol prism analyzermounted in a sliding nickel-plated brassbox. The nosepiece is provided withcentering screws and is slotted in twoplaces to accept accessory sliders. Thetube has a drawtube, the end of which hasa Society screw. It is likely that at onetime, this microscope had been furnishedwith a calibrated B& L polarizing prismas described in the B& L catalog, butthis is now missing. A simple mountingconsisting of a Nicol prism in a brassholder was found with the instrument andnow serves as the polarizer.This microscope was found with its case and the following accessories:A B& L triple nosepiece.Five B& L objectives: 3, 2, 1, 1/2, and 1/12-inch, each with a brass canister.One pair of 1-inch eyepieces, one 2-inch, and one ¾-inch eyepiece for use with the binocular tube.
The ¾-inch is slotted for a micrometer.A single larger diameter eyepiece for use with the petrological tube.A brass adapter that allows the smaller diameter eyepieces to be used with the petrological tube.Two other eyepiece adapters of unknown function.A substage Abbe condenser with iris diaphragm.A substage Wale type iris diaphragm.A Nicol prism polarizer mounted in a brass holder.Four sliders for the petrological tube consisting of a quartz wedge and those marked: 1/4 UND, RED 1. ORDER, and BERTRAND.For comparison, an example theProfessional model (serial #2279) with amonocular tube and glass stage is shown infigure 7.
Another example of;a monocular dating post-1885 with an elaborate mechanical stage having fully calibrated movements is shown in figures 8 and 9. In the 1887 catalog, a monocularequipped with a case and an assortment ofaccessories including 4 eyepieces, 4objectives, camera lucida, and micrometercost $185.00 with the addition of acondenser and mechanical stage the costwas $230.00. From other known examples, it would seemthat the main features of the microscopehad stabilized for most of the remainingdecade. One exception is the fineadjustment mechanism. Most of theProfessionals that one encounters retainthe fine adjustment similar to that originally designed byGundlach and described in the 1876 patent (see Figure 10).A number of examples are known however,such as a binocular #4979 and a monocular#8515, that although outwardly similar tothe microscopes with the Gundlachadjustment, utilize a different internalmechanism consisting of a pair of slideson rollers.
The serial numbers of themicroscopes with each type of adjustmentoverlap and one cannot assume that onetype of adjustment is an evolutionaryadvance over the other. Figure 11 shows theroller focus mechanismmountedas it would be on the microscope.Externally, those instruments that utilize this alternate fine adjustment can berecognized by the presence of two screwson each side of the limb (see figure 12).It is not clear what proportion of theProfessionals produced have this alternatemechanism. Around 1892, the Professional model wasagain altered. This time the changes tothe model were modest compared with thosethat were made in the 1883 model. Anillustration of this form of theinstrument is shown in figure 13.
It isevident that it is similar to the previousversion in most details. The mostsignificant change appears to be with thefine adjustment mechanism in that it seemsfrom the illustration that the microscopenow incorporates the same type fineadjustment that the firm was using withits line of continental models.An example of the very final version of the Professional model is shown in figure 14. This instrument dates from 1894 on the basis of its serial number. It primarily differs from the earlierversions with respect to the shape of the limb and the use of asimilar fine adjustment mechanism that was used with the contemporaryB&L continental style microscopes. This fine adjustment mechanismwas later patented in 1897.
The sub-stage Abbe condenseris also similar to those used on the continental type of microscope manufactured by the firm at that time. The microscope has the B&L patented (1877) slide carrier and glass stage which can be removed and replace with slide clips.By the end of the century, as was the casewith most of the remaining microscopemanufactures, Bausch and Lombdiscontinued the production of large complicated microscopes like the onesdescribed in this article. These were beingreplaced with the much smaller, equallyuseful, and less cumbersome continentalpattern microscopes. But, for many microscope collectors oftoday, the grand microscopes of old, suchas the Bausch & Lomb Professionalmodel, have never been surpassed as theyrepresent the pinnacle of the microscopemaker’s art. Their size, complexity,history, design rationale, and, in oureyes, their beauty, are why we collectmicroscopes in the first place. Referencesand Notes:1.Paggitt,D.
L.,AShort History of the Early AmericanMicroscopes, Microscope PublicationsLtd., Chap. 7, 83,1975.2.Warner, D.J.,ErnstW. Gundlach German-American Optician,Rittenhouse,1,10,1995.3.Gage, S.H.,Microscopy in America (1830-1945),Trans. Microscopical Soc., LXXXIII,No.4, supplement, Chap IV, 27,1964.4.Forillustrations of these models extractedfrom old Bausch & Lomb catalogs see:Reithmeier, G.P.,Microscopes by Bausch & Lomb OpticalCo. Rochester, N.
1876-1896,privately published,1997.5.PriceList of Microscopes Manufactured and Soldby the Bausch & Lomb Optical Co.,37 Maiden Lane N.Y.,1877.6.Bausch & Lomb Optical Co.,Illustrated Price List. Microscopes,Objectives and Accessories,18797.Bausch& Lomb Optical Co.,CondensedPrice List, Microscopes, Objectives andAccessories, Fifth edition,1880.8.Bausch & Lomb Optical Co.,IllustratedCatalogue of Microscopes, Objectives andAccessories, 13 th edition,1892.9.The1892 catalog indicates that an Aug. 15,1882 patent covered the differential screwmechanism. This corresponds togranted to Philip H.Yawman.
It is known (Paggitt, p. 140) thata non-competition agreement was madebetween the Bausch & Lomb and Yawman& Erbe firms in the mid-1880’s. Thepatent rights to the differential screwwere likely transferred at that time.10.Ahas a similar mounting ofthe Wenham prism. It was made by J. Grunow (serial #594) before 1874. Itwould seem therefore that the Grunows musthave priority for this invention and thatthe patent might have been granted toEdward Bausch without knowledge of thisprior art.Acknowledgements:Theauthor would like to thank Paul Ferragliofor fruitful discussions on this subjectand for providing photographs anddescriptions of some of the microscopesfrom his collection.
![](/uploads/1/2/7/1/127194343/319845767.jpg)