Back Button

MICROSCOPE-ANTIQUES.COM     © 2013-20.




THE ORIGINAL FORM OF 'NEW MICROSCOPE' OF POWELL & LEALAND

MAKER: POWELL & LEALAND

MODEL: 'NEW MICROSCOPE'

DATED: 1843

SIGNED ON THE ARM: 'Powell & Lealand, Makers, London' and also dated '1843'

DESCRIPTION HISTORY ORIGINAL OWNER CONDITION

Please Click On Any Picture for a Larger Version, where available

INTRODUCTION:
Although other models were previously made by Hugh Powell, this model, made in the year of its invention in 1843, was the prototype from which all of the best microscopes of Powell & Lealand were to be made over the next 60 years or more. With the exception of their student forms, all subsequent models, leading up to their famed No 1, retained the basic design of this model.

DESCRIPTION:
P & L microscopeP & L microscope This microscope is signed and dated on the arm: 'Powell & Lealand, Makers, London, 1843'. It arises from an English Tripod foot with a span of about 16 cm(6.5 in.) right to left, and 20 cm(7 7/8 in) from either front leg to the rear leg(outside edge to outside edge). Each foot pad is of round profile and cork shod; in the later, larger models, these pads were changed to rectangular, including the 'Improved First Class Microscope' and the No 1 and No 2. The later No 3 retained the round pads.


inclP and L tripodThe right and left feet extend to support the microscope on trunions, one on each side. The tension on these can be changed by adjustment screws on the inner side of each(red arrows); these screws have holes drilled thorough them, to allow adjustment from the side using a small rod or 'Tommy Bar'. The height of the center of the axis of inclination is 127 mm(5 in.) from the table. The top of the rear leg of the tripod has a curved contour matching the round limb to fix the microscope in the horizontal position, while the inner surface has a curved contour to fix the microscope in a vertical position. This tripod is the style which was to form the foundation for P & L microscopes for many decades.


P & L orig microscope The bar-limb construction features an arm that can be turned aside 90o clockwise where it reaches a stop. There is also a stop in the normal forward position. The tension of this swiveling motion can be changed with the adjustment screw on top; like the ones for the trunnions, this screw has holes drilled through it to allow adjustment from the side using a metal rod or 'Tommy' bar. Coarse focus is by rack and pinion. Fine focus is by a horizontally-oriented knob on the right side of the arm acting on a cone inside the arm to move a long lever to the nosepiece. On the front of the limb, just above the attachment to the trunnions, is a receptacle with a hole(diameter of opening about 7 mm), to accept limb-mounted accessories such as a bullseye condenser or a long stage forceps.


P & L orig microscope The mechanical stage is of the type invented by Turrell, with concentric controls. This allows right-left motion along the X-axis, back-and-forth motion along the Y axis, or, when both knobs are turned simultaneously, diagonal motion. The movement along the 'X axis'(right-left) is 'by screw', which in actuality, is a *constant lead cylindrical cam-and-follower design. The movement in the 'Y' axis(forward-backward) is by rack and pinion. The entire mechanical stage is held on a firm stage plate with by four screws from below. The slide being studied is held in position between one fixed and one sliding bar, on a sliding top stage plate assembly. The moveable bar has a sprung pressure-plate, pressing against the edge of the slide to hold it in place. The plate that the upper double-plate slides on can be rotated by hand.

fixed barfixed bar The fixed bar is raised above the surface of the plate by a piece of brass in the center of it. This brass spacer is not rectangular, being narrower in front than in back. As a result, a removable brass insert, which serves as a slide rest, fits in only from the front of this fixed plate, filling in the spaces on either side of the central piece. This arrangement would allow the insertion of an accessory slide-holding piece when the piece inserted is removed. Such a piece accompanied other examples of this model and featured tabs to the right and left side that were higher, for securing thicker types of slides, troughs, etc. Such an accessory insert from another example is shown to the right.


The uppermost 'plate' that the bars are on actually consists of two plates, one sprung against the other, forming a 'safety stage' so that if an objective is accidentally focused down on to the slide, the top part holding the slide gives way, downward. This protects both the slide and the objective from damage due to racking the optical tube too far downward. The entire top double-plate assembly can be manually pushed forward or backward; the fitting on which it slides rotates. When the uppermost plate assembly is pushed backwards, it reveals two holes on the rotating plate beneath it which are designed to receive stage-mounted accessories such as a stage forceps or stage-mounted bullseye condenser. For more images and details about this mechanical stage, please the page about the stage.

*Thanks to Paul Ferraglio for his help in identifying this mechanical arrangement. It differs from a wormscrew design in that the 'screw' does not drive a nut but rather the 'follower', a spring loaded V-shaped piece attached to the moving part of the stage.

The main optical tube has an inner diameter of about 29.8 mm. It is supported not only at the bottom but also by two struts from the arm.

Powell and Lealand microscope The underside of the stage has an attached plate with a cutout to accept a bayonet fitting from accessories. Unfortunately, no such understage accessories remain with the instrument, but those that are known to be associated with this model will be described below. As shown in the engraving, a focusable achromatic condenser assembly was one of the original available accessories, and is discussed further below. Also under the stage, is a swing-in holder for darkwells(red arrows), very similar to the system used later by J.B. Dancer, among others.

The two-sided mirror, flat on one side and concave on the other, is held by a single curved support on one side, a feature used by P & L for many years hence. The curved support attaches to a ring which can can move up and down the tailpiece of relatively large diameter(27mm); it can be rotated on the tail piece. This ring has a two knobs, which when tightened, increase the tension on the ring, reducing its chance of movement and securing it in the desired position.


trade labelorig case The original case(right) features the trade label(left), pasted on to the panel on the inside of the door which reads: 'Powell & Lealand, Opticians, 24 Clarendon Street, Somers Town. This address was Hugh Powell's alone from 1831 to 1841 and was used by Powell & Lealand until 1846 when they moved. At the top of this label is written in pen and ink: 'S.H.Swayne', almost certainly the original owner. Along with the microscope is its free standing bench condenser. This condenser is assembled from two uprights, one screwing into the other to make one long support which in turn screws into the heavy round brass base. The lens assembly is on a T-shaped mount.


ACCESSORIES:
bullseye condOriginally this microscope would have a box fitting inside the original case with accessories. The only accessories with it at this time include a bench (stand) condenser(right), the eyepieces, and the two objectives. In order to give the reader an outline of what other accessories might have originally come with this microscope, I will, in addition to describing these, describe those other accessories found with other known examples.

eyepiecesIn the earliest period this microscope was made, the eyepieces were cylindrical and had a flat top, similar to the one on the far left. The bottom portion of the eyepiece fit inside the optical tube while the upper portion of lacquered brass was the same diameter as the tube, projecting up and at first glance making the tube appear longer. As time passed, the arrangement was changed to the familiar 'top-hat' type of eyepiece, shown to the near left, which were so common in England during that time, and for the next sixty years or more, however the examples used by P & L for these microscopes differed in that they also had part of their sides below the lip lacquered and extending above the optical tube.

PL objectivesPL canThere are two objectives with the instrument. Both are unsigned as was usual for the objectives made by both Hugh Powell alone and also usually by Powell & Lealand, especially in the earlier period. The higher power objective, (obviously made by Powell before the partnership in 1842), comes in its original can signed:'H. Powell, London, 110. The Objectives were made with a thread preceding the standard RMS thread, and so were designed to fit the microscopes of P & L and would likely not fit others without an adapter. The objective range was wide even then, and could include those with correction collars for high power work such as the two objectives with this instrument, including the 1/10th inch objective by Hugh Powell shown here.

Three dark wells were most likely always supplied for this microscope, fitting into the permanently attached substage dark well holder, (red arrows) shown above to the left, which swung into position when needed.

The original cabinet is still with this microscope. It is made of darkly stained mahogany and has a simple frame-and-panel door. Inside the case is a shelf to the left for the accessory case, now lacking. There are also fittings for the parts of the stand-alone bullseye condenser.

accessoriesbig stageMost of the accessories of an identical microscope, made in 1844, from a private collection are pictured to the left in their original case. They include an understage simple wheel of apertures, a lensed understage condenser, a limb-mounting bullseye condenser, two live boxes, multiple objectives, multiple eyepieces, three darkwells, a stage forceps, a hand forceps, a substage polarizer, a Soemering-type camera lucida, lieberkuhns, a supplementary slide rest*, and an eyepiece analyzer. Some examples have a prism which attaches to the bottom of the condenser via a round clamp, to be used instead of a mirror. With this same example, and fitting separately into a drawer in the main case, are an eyepiece micrometer, a lever compressor, a large frog plate, and a larger top stage plate(right) designed to be used in place of the other top plate for larger slides and apparatus, like the frog plate. Unlike the main stage plate, this plate is not sprung as a safety stage and is therefore, although larger, it is at the same time, thinner.

*this attached under the fixed slide rest on the sprung stage plate and protrudes upward thus more firmly securing thicker accessories.


P and L condenserP and L disk of aperturesOf particular interest, are the understage accessories for for use with transparent objects. When these microscopes were first made, a condenser without provision for stops or adjustment of aperture was provided with the instrument(left). Because the stage is quite thick, the tube of this condenser has to be relatively long. To be able to focus it, the rack and pinion apparatus had control it from below the underside of the stage. A separate wheel or disk of stops was also provided(right). Both of these pieces of apparatus have lugs to allow installation via the bayonet fitting under the stage.

P and L condenserBy the 1850's, as shown in the illustration to the left from the 1856 volume of Carpenter's The Microscope and Its Revelations, a more complicated condenser could be supplied. It provided built in stops. To achieve this, it not only had to attach to the underside of the stage by a bayonet fitting, it had to be able to fit inside the deep stage so its top lens could approach the bottom of a slide. To do this, its stops were in two disks(or wheels), thereby reducing the size of the disks so they could fit into the relatively small opening in the bottom of the stage. Furthermore, the entire apparatus had to be adjusted from below, by controls projecting below the bottom of the stage. The two controls for the wheels of stops were concentric and there were markings to indicate which stops were in the optical path. This anticipates, to great extent, and was undoubtedly the inspiration for, the later substage-mounted Ross Improved Gillette Condenser. The rack and pinion focusing of this P & L condenser was also controlled by a knob on a fitting protruding below the understage mounting. Although rack and pinion substages were being added to the larger transitional P & L models no later than 1856, the integrated rack and pinion substage was not used on this smaller size of microscope until the No 3 model came into existance in the 1860's.

CONDITION AND RARITY:
This microscope, considering it is more than 175 years old, is in good condition. The stand shows varying degrees of lacquer loss especially on the top of the stage and to lesser degrees on the support struts, the arm, and the tripod. The optical tube has a slightly irregular finish but actually looks quite good. The eyepieces are not original, but are accurate-appearing period replacements. The objectives are both in good condition with working correction collars. All the controls work very well. The stage fittings all function as they should. The stand-alone bullseye condenser has substantial lacquer loss and one screw is a modern replacment. The glass is excellent. The case has cracks, areas of missing molding, and is missing some of its interior furniture as well as the accessory case. None of the substage accessories with bayonet fittings are extant. The hinges for the case are sound and there is no key.

This model was apparently quite popular in its day as there are a number of examples that have survived. Examples like this one, from the first year of production, are less common than other years. Overall, this remains a beautiful and impressive instrument, the prototype for Powell & Lealand microscopes for the next 60 years or more.



HISTORY OF THE POWELL & LEALAND No 1 MODEL MICROSCOPE STAND

We are grateful to Dr Jurriaan de Groot for writing the the majority of the following history:

1843 original Although larger model microscope stands had been produced by Hugh Powell, notably the massive stand commissioned by the Royal Microscopical Society in 1840, what is now known as the No 1 Model was a direct development of Powell & Lealandís 'New Microscope' of 1843, the model featured at the top of this web page. These microscopes of 1843 formed the prototypes of the famous group of stands, later to be called the Powell & Lealand Number 1, Number 2, and Number 3. In fact, this microscope is often confused with the later Number 3 stand, which it resembles in many ways. As shown here, this form stand was first described in the 1843 November issue of The London Physiological Journal as 'Powell & Lealandís New microscope'. This stand is supported by a lighter, but still very strong, version of the tripod, than P & L's later first class stands. It carries the body on trunnions, and has a transverse arm, which contains the long lever, which moves the nose piece fine-focus adjustment. Initially, as seen on this example, the fine-focus screw, which operated a cone, was placed on the right side of the arm. Likely because the cone was prone to wear, this was moved to the familiar vertical position on the top of the arm in 1847. At this point in its development, the microscope tube was also supported by a set of diagonal stabilizing struts extending from the back of the arm to the upper third of the tube. Sometime during the early 1860's these were abandoned.


p and l 1856 Powell & Lealand did not enter the 1851 Great Exhibition, but it is believed that during this time they worked on a larger model based on the original design. Dated examples are extant from this period, with the more solid rectangular feet as in the later No 2 stand, either with or without the supporting struts. These could be regarded as the 'proto-No 1/No 2 stands', from which the later models were developed. An example of one of these, called the Improved Large First Class Microscope is found on this site, and still has struts supporting the tube. As seen in the image to the left, this stand of 1856, is essentially the same as the 1843 stand, other than the position of the fine focus knob, the design of a heftier tripod, and the rectangular and heavier tripod legs. More importantly though, it now had a separate rack and pinion substage, so substage accessories no longer were attached to the bottom of the stage itself.


No 1 about 1861 The next model(left), was worked on at odd times, and appeared in 1861. It was similar in outline and appearance to the final No 1 design, save for the massive ring attached to the limb, within which there was a second ring carrying the stage to which the substage was attached, allowing both to be rotated by the same rack-and-pinion movement, with separate rotation also provided for the substage. An example of this model was ordered by the Radcliffe Library for use by The University Museum, Oxford, in 1864, together with a 1/50-inch objective amongst the accessories. We should also note that Wenham's binocular, first seen about 1860 was added to the Powell & Lealand options and further improved upon over the years. The No 1 model continued to be made as described above until the definitive version of the No 1 model stand was put on the market in 1869. The main modifications involved the construction of the rotating stage, which this time was mounted in the same plane as the ring, and there was a separate carrier for the centering and rotating substage, attached below the stage now, and not rotating with it as in the previous model.


No 1In this final form, the Powell & Lealand No 1 microscope continued to be made unchanged for another 40 years, until the firm quietly faded out of existence during the first decade of the 20th Century. The only additions, were an optional fine adjustment to the substage (1882), rack work to the monocular draw tube (1887), and diagonal rack work to the coarse adjustment, all at the suggestion of E.M. Nelson, an eminent microscopist, and user of this model. For more information about P & L, including a detailed and illustrated description of the final form of the No 1, as well as a more detailed history, please see the Powell & Lealand No. 1 page

As the No 1 microscope of P & L evolved, so did their other microscopes. In fact, all the previous models were apparently abandoned, and the No 2, 3, and 4 were all derived from the original 1843 model. For a comparison of the later No 3 and the microscope featured at the top of this stage see the compared engravings page. Eventually, only their student stands, No 5 and No 6 differed in their basic design. The P & L student microscope No 5, also referred to as the 'Iron Microscope' because part of it was usually made of black-painted iron rather than lacquered brass, was a much more basic design. We are not aware of any illustration of the Student Microscope No 6, but it may have been a Ross-type of Bar Limb as several such stands signed by P & L, and equipped with P & L accessories, do exist.


THE ORIGINAL OWNER:
The trade label in the case identifies the owner as 'S.H. Swayne'. Samuel Henry Swayne, M.R.C.S. Eng, L.S.A.(1820-1900), was a physician who trained at Bristol Medical School and St Bartholomew's Hospital, earning his M.R.C.S.* in 1843, the year this microscope was made. He earned his L.S.A.* in 1844. He was, for some time, in medical practice with his more famous brother, Joseph Griffiths Swayne. J.G. Swayne had obtained the same degrees as his brother two years earlier, in 1841. The brothers taught 'General Anatomy and Physiology accompanied by 'Microscopic Demonstrations' at the Bristol Medical School in the 1840's. They also spent some time in Paris, which may explain why the microscope described above on this web page was found in Paris in the 21st century. It is unlikely to be a coincidence that this microscope was made in the year S.H. Swayne obtained his M.R.C.S, and that he taught classes that included demonstrations under the microscope. At that time, this microscope would have been considered one of the latest and most modern microscope available, and may have been used for 'demonstrating' microscopical parts of the course the Swayne brothers taught.

*M.R.C.S=Member of the Royal College of Surgeons and L.S.A.=License of the Society of Apothecaries; M.R.C.S. was the initial qualification for a general practitioner in England, but was also granted to surgical specialists until a little later when they were distinguished by F.R.C.S.