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tolles scopes

INTRODUCTION: This page is devoted to the known designs of microscopes by the renowned American microscope maker, Robert B. Tolles(died 1883) and his foreman and successor, Charles X. Dalton.

Robert TollesRobert Tolles(left) was a remarkable man who grew up without means. He could not afford to attend college, but instead when old enough, set out to find a suitable employment. On his journey he happened to pass through Canastota, New York and came across the workshop of the famous and very talented Charles Spencer. He immediately decided this was the profession for him and he stayed as an apprentice and then workman for Spencer, spending about fourteen years with Spencer.

In 1858 Tolles went into business on his own in Canastota, where he became famous for the quality of his work. By 1867 had moved to Boston to superintend the Boston Optical Works (BOW). Tolles continued to use the profile of the foot and limb that was used at Spencer when Tolles was working there. The BOW was dissolved as an entity about 1872 but Tolles continued to run the business, while Charles Stoddder, the founder of the BOW continued to sell Tolles products as his agent. Charles X. Dalton was working with Tolles at the Spencer company and followed him to the BOW.

Tolles, a talented optician, produced relatively few stands compared to the number of optical parts that he fabricated. The reason for this was obvious as he was fascinated and obsessed with improvement of the optics of microscopes. This talent resulted in some of the best optics ever made and, among other things, the invention of oil immersion objectives which made use of softened Canada Balsam as an immersion media. Tolles inventions included many other notable achievments including high power objectives with some of the highest numerical apertures ever achieved. Tolles companies also produced well made microscope stands, the brasswork mostly by Dalton. Among the most plentiful of these still in existence are his student stands, including several variations of the one shown on this site. For a more comprehensive history of the life of Robert Tolles please see Dr Brian Stevenson's review on his website, Historical Makers of Microscopes and Microscope Slides.

Tolles died in 1883, and Dalton ran the company until it ceased operations. Dalton's knowledge and understanding of optics was second to none and his objectives were known as being on par with the best in the world.

After a catastrophic fire at his works in Chicago, Walter Bulloch also worked for Tolles from about 1871 to 1872. Some of Bulloch's influence can be seen on the late version of the Tolles 'A' stand(constructed by Dalton) in this collection. It is very clear that Dalton was heavily involved in the designs of Tolles microscopes even when Tolles was alive, as evidenced by the wooden model of the 'A' stand from 1876 in the Harvard collection, signed by Dalton. It is well known that Dalton did much of the Brass work for Tolles who himself concentrated on the optical parts. In 1868 the BOW advertised in the Boston Journal of Chemistry Tolles First Class Trunnion Microscope and also Smith's Inverted Microscope for Chemists. The 1873 BOW catalog with Stoddard as agent, notes that the BOW also sold microscopes by Zentmayer, objectives by Wales and the Bulloch self-centering slide-ringing turntable.

Tolles (Boston Optical Works) Catalogs from the late 1870's and early 1880's describe the following six models:
The Student Model
The Pocket Microscope
The Professor's Microscope
The 'A' (the largest and heaviest)
The 'B' (standard large second class* microscope)
The 'C' (The 'B' with sector rotation to the substage)

Although Dalton apparently never published a catalog which listed his own designs of microscopes, other types of Tolles-BOW-Dalton microscopes are known, and include a compound monocular Botanical Microscope of unusual construction signed by Dalton, and an inverted Tolles Chemical Microscope after Lawrence Smith. There are three wooden microscope models attributed to Dalton at Harvard University. One is the prototype for the 'A' stand, the other two are clearly one of a kind wooden instruments. Because no illustrated catalog of Dalton stands per se seems to exist, it is difficult to know what Dalton actually offered as standard instruments. Very few microscopes with Dalton's signature are known, and even then, the signature is hidden on at least his A stand in this collection. For now, as far as Dalton's models are concerned, all we can do is review the examples that are currently(2021) known. It should also be noted that Dalton also sold microscopes by other makers including Zentmayer and Bausch & Lomb of the U.S.A. as well as Leitz and Fuess, both of Germany. In these instances, Dalton's trade card is to be found inside the door of the cabinet in which the instruments were sold. For more about C.X Dalton please see the History Section of the page about the "A" stand constructed by Dalton.

Tolles did not follow the convention of the time of first class, second class and third class instruments, but rather named his instruments by purpose or with a letter. This makes sense to anyone who has seen a Tolles microscope because his A,B, and C stands and the objectives supplied with them are all of high quality.



Tolles 'Pocket Microscope' also called his 'Clinical Microscope' was basically in the form of what most makers would call a 'demonstration microscope' and consisted of only a stage and focusing optical tube to be hand-held. Coarse focusing was by sliding the outer tube and fine focus was by turning the threaded inner tube at the bottom near the objective.


This was similar to the pocket microscope, except it provided a mechanism to lock the slide in place so that the object being studied did not shift as the microscope was passed from student to student.


Tolles' Student Microscope was an instrument of high quality for its intended use. This model was not only intended for 'students' but was also promoted (and good enough) for physicians to use. It was available in standard form with a black painted finish or for extra cost, in lacquered brass throughout. It came standard in a walnut case with push-pull coarse and Tolles excellent nosepiece fine focusing; instead of the nosepiece fine focus, the tilting-stage fine focus was an option for a $20 discount. A concave mirror was standard which could be removed from the microscope to slide onto a stand supplied with it to allow for illumination of opaque objects from above. Also included was a substage disk of apertures, a single B eyepiece and a 1/4 inch and 1 inch 2nd quality objective.
As revealed by the 1872 price list from Frey, the buyer had the option of several upgrades for additional cost. These included rack and pinion coarse focus, a substage for accessory apparatus, drawtube, plain mirror, rotating glass stage, and a device for using a maltwood finder. The example shown here has the optional rack & pinion coarse focus and optional all-lacquered brass finish with the downgrade of stage fine focus. The student model is by far the most common type of Tolles microscope encountered nowadays.



Although C.X. Dalton had done much of the brasswork for Tolles, after he took over the Boston Optical Works he produced some stands that shared some features of Tolles designs but also changed or customized the designs. This is an example of such a stand, images of which were kindly provided by its former owner, Bill Burnett and its current owner, Tom Schwan. The author is also grateful to Tom Schwan for assisting with this section about this microscope. This stand has the classic BOW tapering bowed limb. In common with the Tolles Student model, this stand arises on two flat uprights. Also in common with the student model is the fact that there is a simple stage, not any form of mechanical stage as is found on the earlier and much larger Tolles B stands. But instead of being square, the stage on this microscope is round. The main differences between this Dalton stand and the Tolles Student model, are the addition of a swinging mirror tailpiece, and a rack & pinion focusing substage. It has the same narrow tube as the Student model, not the wider diameter of the B stand. As is shown in the table and image below, this model is only slightly larger than the Tolles student stand and slightly heavier than the Tolles student,but much lighter and smaller than a B stand. Its proportions are not close to any of Tolles known B stands or the A stand. Its swinging substage is nothing like the more sophisticated one on the Tolles-Blackham microscope(shown below) and much more like the simple swinging substage of the Beck Ideal Model This then represents Dalton's modified version of a stand very much like the Tolles Student microscope, and of only slightly larger proportions. It is more like the Tolles Student Model than the larger and much heavier B Stand.

Tolles Student15.25"8.4 lb
Dalton Student16.25"9.8 lb
B stand19.25"17.6 lb
A Stand18.25"18.5 lb
*height of the microscopes is compared with the tip of the 1 inch Tolles objective racked down to the stage, and the microscopes in a vertical (not inclined) position with no drawtubes drawn out; in the case of the binocular, the interocular adjustment is racked down.

3 scopes


b stand
The 'B' stand was Tolles' most popular second class* microscope. It was extremely well made and was used by many for work that was very demanding, attesting to its quality. It was often sold with Tolles best objectives, not the 2nd quality objectives supplied with his student microscopes. It weighs about 14 pounds and sits on a modified Y-shaped foot with round pillars supporting the limb. It has a 5 inch diameter mechanical stage that could be rotated. It came in a dark walnut cabinet. Although it did not come standard with a tilting substage, an attachment to the tailpiece of this stand would allow very oblique illumination with a microscope objective used as a condenser. The author is grateful to Allan Wissner for allowing me to use his images of this microscope. Tolles B stands are quite uncommonly found these days and most are coveted by their owners, often coming well equipped with many high quality objectives.


A stand

The A stand was Tolles' and Dalton's biggest and best microscope. This example was made by Tolles' Foreman, Charles X Dalton in 1886, soon after Tolles had passed away. Dalton advertised himself featuring Tolles' microscopes. It features binocular tubes, short lever nosepiece fine focus, swinging substage with rack and pinion focusing, a separate swinging tailpiece for the mirror, centering for the condenser and an equilateral flat tripod foot with rotation for the stand which can be locked. The stage is Tolles thin type, and can rotate completely, featuring a concentrically controlled Bulloch-type mechanical stage. As of the date of this writing, the A stand is an extremely rare instrument, and the author knows of no other extant example made of metal. The reason for the rarity is simple. This stand cost nearly one third more than the B stand, shown above, and the B stand is an extremely well made microscope. It was available with the most important features of the A stand. The main difference was the type of foot, and the fact that the A was slightly larger and 25% heavier than the B. In keeping with this, the stage had a 6 inch diameter as opposed to the 5 inch diameter stage of the B stand-see below. Lastly, at least in this example, the substage could be tilted to any angle, making the best use of the thin stage thus allowing the most oblique illumination. The mechanism of tilting or swinging the substage is clearly a copy of the type devised by Zentmayer and especially Bulloch who first constructed it with a separate swinging tailpiece for the mirror which could be swung differently than the substage if desired.


c standc stand

In 1878, the first version of the Tolles-Blackman microscope(left) was reported in the JRMS and it was first pictured in the Journal in 1880. The example from 1878 was reportedly owned by Mayall. In 1880 it is reported that it was first made for Dr George Blackham, MD, FRMS. Blackham was a famous microscopist, an early member of the American Microscopical Society(AMS), and good friend of both Charles Spencer and Robert Tolles; he was the author of Tolles' obituary published in 1884 in the AMS journal, Proceedings of the American Society of Microscopists. Dr Blackham was the author of a famous publication, read before the Microscopical Congress in 1878 and published as a booklet in 1880 entitled On the Angular Aperture of Objectives for the Microscope. The Tolles-Blackham(T-B) microscope had the same foot as the 'B' stand and it may be the microscope referred to in the BOW catalogs as the 'C' stand. The microscope on the right is a later version of the T-B microscope reported in the JRMS of 1881. These microscopes were equipped with the Tolles sector or patent radial arm for the substage, which carries the illumination above the stage, and measures the angle of incidence of light above or below the stage. This is a mechanism similar to many other microscopes of the time, popular when very oblique lighting was in vogue and thought to be a way of increasing resolution. This was sometimes even applied to third class microscopes like the Beck Ideal Microscope, and as noted above, a simple version of swinging substage is found on the Dalton Student stand pictured above.


This unusual microscope is recorded as a botanical type in the Harvard records, though why this is stated is a mystery to this author. It is signed by Dalton and the curator noted that it is constructed to a very high standard. It was specially made for F.H. Peabody in 1890. Peabody was a prominent banker, member of the Boston Natural History Society, and a member of the New England Botanical Club.


This instrument is the Tolles-BOW version of the inverted chemical microscope invented by Dr J Lawrence Smith. It was first produced by Grunow in the 1850's and versions of it were also made by Bausch & Lomb in the U.S.A. and Nachet in France.

*At the time, some authors classified microscopes into first class, second class, and third class instruments. First class microscopes were of the most complex type, supplying every facility the maker thought could ever be required, even if not needed by the usual user. The second class instruments were those usable by most people wanting to do high quality work, without the usually unnecessary bells and whistles of the first class. Third class microscopes were student stands supplying the basic needs of a student, and other lesser stands. Although the B and C stands are technically second class instruments by convention, they were for most purposes, constructed with such high quality they were equal to, or better than, any first class instrument of the time.