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ANTIQUE MICROSCOPES AND OTHER ANTIQUE SCIENTIFIC INSTRUMENTS

MICROSCOPE-ANTIQUES.COM     2013-2017


COMPRESSORS OR COMPRESSORIA

comp

INTRODUCTION A PARTIAL LIST OF COMPRESSORS

 

INTRODUCTION:

As interest in studying living (and moving) organisms grew, various methods were devised to allow this to be accomplished under the microscope. In its most basic form, a moving organism was followed using a moveable stage, or better, a moving set of optics such as was devised for the 'Trembley-Ellis Aquatic' type of microscope. Another method is to use a 'live box' also known as a 'live cage' or 'Animalcule Cage.'   This device was designed to observe living specimens such as protozoa in a liquid medium. It could also simply trap an insect in an enclosed space. In some cases, some degree of pressure could be applied to the top cap of these live-boxes to try to immobilize moving specimens, but the adjustment of these devices is imprecise and it was hard to get just the right pressure for certain purposes. Hence the Compressor or Compressorium was devised and this page is about them. In the near future, a page devoted to live boxes will also be found on this site. Varley's version of the livebox, which he described as his 'Capillary Tablets or Cages' in the Journal of the Society of Arts, Volume 48, Part II, pages 343 to 344 in 1831, could be used as a compressor because its top screwed down. This was also problematic, for although the pressure could be slowly adjusted, the rotation while screwing down could distort the specimen.

purkinjeThe famous histologist Purkinje is often credited with inventing the first dedicated compressor about or before 1834, though he used it to flatten histology sections rather than immobilize moving organisms. The Purkinje compressor was described and pictured, (in German), in Muller's 'Archiv fur ANATOMIE, PHYSIOLOGIE UND WISSENSCHFTLICHE MEDICIN... The compressorium or compressor, is therefore, an instrument which evolved from the live box, but allows both a finer adjustment of the pressure applied and also, if needed, a higher or lesser and subtle degree of pressure. It therefore can also be used, unlike the live box, to crush specimens and make them thinner and more transparent allowing transillumination or it can also be used for very delicate work, as in immobilizing motile protozoa. Many variations of this device were produced over the years, and the most recent version, the Taylor compressor, is a late 20th century improvement on Rousselet's invention. Some variations allow a relatively limited amount of pressure (i.e. the gravity compressors), while others, like the Lever compressor allow a considerable amount. The large glass plate compressors used to flatten teased pieces of meat during inspection for trichinella larvae can apply even more pressure. Between these extremes are the Lister compressor (by James Smith and successors) and the Beck parallel plate compressor. Most of these instruments allow one position of use, but the Parallel plate devices can be reversed, as can Ross' Reversible Compressorium; Piper's compressor allows full rotation of the (relatively small) compressor permitting even more angles of observation.

Although Varley's original live box, can also serve as a compressor, and has a screw-on top, allowing fine adjustments, this method was abandoned, as the twisting motion so applied often distorted the specimen. For this reason, later versions of his design have a press-fitting cap and were less used to apply pressure to the specimen but to simply observe a thin layer of a liquid medium.

trichinoscope In the late 19th century, dedicated Trichinoscopes were sold in large numbers for meat inspection. Although these were usually just low power microscopes with a larger stage and a large glass compressorium, some examples with integrated compressors were made such as that by Schmidt & Haench. Although in the past a heavy glass compressor was used to flatten teased out fibers of meat to make them translucent, in order to inspect the meat for trichinella larvae, the process of meat inspection by this method was made a bit easier by partial digestion of the meat with enzymes. More recent methods use a more complete digestion of the muscle and the parasites are found in the sediment, and are examined with a stereomicroscope without the need for a compressor.


NOTE: All of the compressors shown on this page are in the author's collection except for the Varley, Bulloch, Simpler Ross Reversible, and Piper examples from other private collections. I am grateful to the owners of these for allowing me to share them with you. Please note that I have not attempted to show every compressor ever invented, as there are simply too many of them, and I do not (and could never) have examples of all of them, but I do think this is a good representative sample of the most common types.

 

PARTIAL LIST OF COMPRESSORIA


PLEASE CLICK ON THE IMAGES FOR MORE INFORMATION, WHERE AVAILABLE

APPROXIMATE
DATE
NAME IMAGE TYPE
c. 1834
or earlier.
PURKINJE
COMPRESSORIUM
PurkinjeSCREW TYPE
c. 1841
or earlier, through the 1890's.
LISTER
COMPRESSOR
listerLISTER SCREW TYPE
c. 1841
or earlier
SCHIECK
COMPRESSOR
leverLEVER PRESSURE TYPE
c. 1842YEATES
COMPRESSOR
yeatesPARALLEL PILAR
There are three upright pillars around the rings. The top glass was held in place by the clips at the top.
c. 1855-?BROOKE-TYPE
GRAVITY COMPRESSORIUM
brookeGRAVITY COMPRESSOR
c. 1855-BECK PARALLEL
PLATE COMPRESSORIUM
beckPARALLEL PLATE COMPRESSOR
c. 1862-HIGHLEY
COMPRESSORIUM
HighleyLEVER COMPRESSOR USING A STANDARD SLIDE AS THE BOTTOM SURFACE
c. 1862-72ROSS
COMPRESSORIUM STAGE
rossCOMPRESSORIUM STAGE WITH SWING OUT COMPRESSOR
c. 1868PIPER REVERSIBLE
COMPRESSORIUM
piper compROTATING REVERSIBLE TYPE
c. 1869-?ROSS REVERSIBLE
COMPRESSORIUM
rossPARALLEL PLATE TYPE
c. 1869-?ROSS IMPROVED
REVERSIBLE
COMPRESSORIUM
rossPARALLEL PLATE TYPE
after 1870HIGH PRESSURE
TRICHINOSCOPE
COMPRESSORIUM
rossPARALLEL GLASS PLATE TYPE
c. 1870'S?-WENHAM
COMPRESSORIUM
rossSIMPLE SPRUNG TYPE
c. 1880-FOL
COMPRESSORIUM
FolA PILLAR SCREW TYPE, SIMILAR TO ROUSSELET'S BUT WITH THE TOP PLATE ADJUSTIBLE WITHIN ITS RING
c. 1880-FOREST
COMPRESSORIUM
ForestA SIMPLE SPRUNG COMPRESSOR, SIMPLY THE OPPOSITE OF THE WENHAM
c. 1880-GRAHAM
COMPRESSORIUM
GrahamPRECURSOR OF THE ROUSSELET TYPE
c. 1880-HOLMAN
COMPRESSORIUM
HolmanSIMILAR TO THE GRAHAM, EXCEPT THE BOTTOM PLATE IS MOVEABLE AND THE TOP PLATE FIXED
c. 1882-HARDY
COMPRESSORIUM
HardyA HINGED COMPRESSOR WITH PRESSURE ADJUSTMENT ON TWO SIDES WHICH ALSO ALLOWS ADJUSTMENT FOR PARALLELISM
c. 1880's-BULLOCH
COMPRESSORIUM
BullochFEATURES OF BOTH THE WENHAM AND HARDY COMPRESSORS
c. 1883BAUSCH & LOMB
TRICHINOSCOPE COMPRESSOR
B AND LA HINGED TRICHINOSCOPE COMPRESSOR WITH INTEGRATED SIMPLE LENS FOR FIELD USE
c. 1883BAUSCH & LOMB
COMPRESSOR
B AND LA SPRUNG COMPRESSOR WITH TWO PINS TO KEEP THE PLATES PARALLEL
c. 1884VIGIEUR
COMPRESSOR
vigieurA SIDE PILLAR COMPRESSOR WHICH ACTS ON AN ORDINARY SLIDE AND COVER SLIP
c. 1886JUNG'S STAGE-MOUNTED
COMPRESSOR
jungA LEVER COMPRESSOR WHICH ACTS ON AN ORDINARY SLIDE AND COVER SLIP
c. 1886DELAGE REVERSIBLE
COMPRESSOR
delageSIMILAR TO THE LEVER TYPE BUT WITH SCREW ACTING AGAINST A WEDGE; MADE BY NACHET
c. 1886G. WATSON REVERSIBLE
COMPRESSOR
g. watson compressorA ROTATING COMPRESSOR WHICH IS VERY SIMILAR TO THE PIPER MODEL OF 18 YEARS EARLIER, BUT WITH LARGER PLATES AROUND THE COVER SLIPS.
c. 1889SCHULZE'S STAGE-MOUNTED
COMPRESSOR
jungA LEVER COMPRESSOR WHICH ACTS ON AN ORDINARY SLIDE AND COVER SLIP; IT CLAMPS TO THE STAGE WITH A 'C' CLAMP.
c. 1889DIAMOND TOP
GRAVITY COMPRESSOR
diamondA GRAVITY COMPRESSOR OF SIMPLE DESIGN
c. 1890ROUSSELET
COMPRESSOR
rousROUSSELET TYPE
c. after 1895IMPROVED ROUSSELET
COMPRESSOR
rousMODIFIED ROUSSELET TYPE
c. 1899DAVIS EBONITE
COMPRESSOR
davisDIRECT SCREWING PRESSURE TYPE
(similar to Lister type without the springs)
c. 1988TAYLOR
COMPRESSOR
taylorROUSSELET TYPE

 

COMPRESSORS:

THE VARLEY 'CAPILLARY TABLET'

compressorAlthough usually considered a livebox, Varley's 'Capillary Tablet,' with its screw-on top, could be used to apply compression to the specimen. For this reason, it might be considered an early form of compressor as well as a live box.

BROOKE TYPE:

compressor compressor
compressor
compressor

This type of compressor is one of a class known as 'gravity compressors.'   This means that the pressure applied to the specimen is limited to what the weight of the top pressure plate applies without any leverage or springs to apply a greater amount of force. The bottom plate of brass has a central hole. Over this hole is the bottom support for the specimen made of glass. The top plate, with thin glass on its bottom surface, rides freely on two vertical pins. The distance of the bottom of this top plate is regulated by three thumbscrews which project from its bottom and act like little 'legs.'   As each screw is loosened, the weight of the top plate brings the glass on its bottom closer to the glass on the bottom plate. The maximum pressure applied, is simply a function of the weight of the top brass plate. This device has advantages of easy access, low cost, and easy cleaning. Disadvantages include the need to adjust three different thumbscrews to apply equal pressure all around the object being studied, and the fact that more severe pressure, beyond the weight of the top plate, cannot be applied.

LISTER TYPE:

compressor compressor
compressor compressor
compressor

The Lister compressor, also referred to (by Beck) as a 'screw live box,' was first manufactured by James Smith. It is a compressor with springs to apply greater pressure than that of the gravity compressors. It consists of a bottom brass plate, with a cylinder permanently erected upon it; at the top of this cylinder is permanently mounted the bottom glass surface, just like a live-box. The difference though is that the outside of this cylinder is threaded and a large knurled ring rides in these threads. The top plate of the compressor rides on two upright posts, with springs applying downward pressure against the knurled ring on the bottom plate cylinder. If the knurled ring is screwed all the way down, the glass in the top plate is pressed against the glass at the top of the cylinder with the full force of the springs. If the knurled ring is unscrewed, it pushes up on the top plate, lifting it off the bottom glass.

The glass on the bottom part has beveled edges. There are two steel tabs on top of the top plate to hold a cover slip in place. When the ring is unscrewed, it pushes up on the top plate, and when screwed down, it allows the top plate, pushed down by the springs, to compress the specimen upon the bottom glass support. In effect this allows a fine degree of adjustment to the degree of compression, which is more forceful than the gravity types due to the springs.

In use, the knurled ring is unscrewed all the way up with no cover slip on the top plate. The specimen is then placed on the glass at the top of the cylinder of the bottom plate; once the specimen is in place, a cover slip is placed under the two steel clips of the top plate, and the knurled ring is slowly screwed down until the desired degree of compression is achieved. The top plate has a straight edge against which a coverslip with one flat edge can register.

The Lister compressor was made and sold by James Smith no later than 1840, continued to be sold by his successors and was still offered in the 1891 catalog of James Swift & Son. Ross also made a variation of the Lister compressorium, with four instead of two upright posts. The Lister compressor has an advantage over many others in that it is a very simple matter to change the top cover glass by simply moving the spring steel fingers away.

LEVER or SCHIECK TYPE:

compressor compressor The lever compressor, allows direct pressure to be applied to greater degree than the other compressors shown above. A spring, which pushes the covering glass end of the lever upward, keeps the compressor from applying pressure except as applied by the opposing thumbscrew. This type of compressor may have been invented by Schieck and in German texts is often referred to as a Schieck Compressorium. In Schieck's compressorium, a notable difference from the British versions was the presence of three upright pins which would allow it to be reversed on the stage, though of course now much higher off the stage. Changing the cover glass in this compressor requires removing the old one and gluing on a new one. One way of making this easier was to use a glue consisting of a mixture of, e.g., Canada Balsam and Beeswax.

ROSS SWING-OUT COMPRESSORIUM STAGE (1862-72):

compressorThis compressor was apparently first exhibited by Thomas Ross in the Great Exhibition in London in 1862. It was designed to sit firmly on top of the existing stage with pins holding it in place. The compressorium could be completely swung out of the way, leaving the stage with a typical slide rest. In operation, a normal slide and cover slip would be used, and the compressing plate, N-M would be lowered on top of the cover slip with pressure regulated by the knurled knob P. (Thanks to Jim Solliday for information and images of this compressor).

PARALLEL PLATE TYPE (BECK):

compressor
compressor
compressor

compressor The Beck Parallel Plate compressor is constructed in such a way that it resembles a parallelogram. Its chief advantages are its thin profile and reversibility. The illustration above to the right shows one of the glass supports removed. There is one for the top plate and one for the bottom. Cover glasses are glued to these metal disks which lock into place and it makes it a much simpler matter to clean them or replace them. Again, a glue that contains some beeswax would make removal easier. Most surviving examples of the Beck Parallel plate compressor are missing these round metal fittings to hold the cover glasses. To use this device, the two plates are pushed together after the specimen is placed on the bottom glass. The springs push the two plates apart thus maintaining tension. When the two plates are relatively close to one another, as the horizontal screw fixed to the lower plate is advanced (A-->B), its tip engages with an angled channel(*) in the black metal attached to the top plate, drawing the top plate downward. Although it appears this device would maintain parallelism, this is not necessarily the case, as illustrated by the image below. In addition, as it is tightened further, it can bend.

compressor

ROSS' REVERSIBLE TYPE (?1869-?):

compressor compressor Ross made two versions of a reversible compressor. This is the thinner and simpler of the two. In his 1869 and 1872 catalogs, Ross offered a 'Ross Reversible Compressorium' By 1875, the 'Ross Improved Reversible Compressorium'(IRC) was listed. Strangely, the IRC was pictured in the 1875 catalog, but the illustration in the 1883 catalog seems to be the this less sophisticated model, with the caption still referring to the IRC. This model is harder to use than the next entry. In use, according to Dr. de Groot, the user needs to apply some manual pressure to the top plate while tightening the knob in order for it to properly compress the subject. The top plate rides in the angled grooves(*) on the right and left side of the bottom plate, and as the screw is tightened the top plate is pulled downward as it pushes further into the matching grooves. There are convenient tabs to hold cover glasses on each inside surface of the compressor. (Collection of Dr. Jurriaan de Groot).

ROSS' IMPROVED REVERSIBLE TYPE (1869-):

compressor
compressor
compressor

compressorcompressorcompressor The 'Improved Ross Reversible compressor,' first reported in the Monthly Microscopical Journal of 1869, was apparently offered in Ross catalogs from 1869 through at least 1883. The main part of the instrument consists of an 'I-beam'-shaped base plate with a threaded hole into which screws a knurled ring onto which a glass base plate is glued. On the opposite side, as shown to the right, a secondary plate, A, also with a knurled theaded ring carrying a thin glass plate, floats between three keeper posts, B.   This secondary plate is pushed away from the main plate by two springs pushing up from the bottom plate(not shown, but virtually identical to the those in the preceding Ross entry). The secondary plate has wedge-shaped top edges, C.   The two-pronged fork, with a wedge-shaped tine on each side, D, sits on top of the floating secondary plate. As the worm screw, E, is turned, it advances the fork which pushes down on the secondary plate. The tines of the fork are kept in contact with the bottom plate by a ledge, F, on either side of the compressor. This compressor was apparently Ross' answer to the Beck Parallel Plate compressor as the catalogs referred to it 'for securing parallelism of the surfaces.'   To this author, this type is more likely to achieve that goal than the Beck, which could bend as tightened and did not remain parallel despite its parallelogram design. This model of the Ross Reversible Compressor seems to work much better than the other Ross Reversible Compressor. Again like several other examples, the cover glasses must be glued into the knurled rings; beeswax in the glue would make them easier to remove or replace when needed.

PIPER TYPE:

compressor compressor The Piper compressorium was reported in the JRMS in 1868 by Samuel Piper. This compressor has the advantage of complete rotation, allowing a variety of angles for viewing without removing the compressor from the stage. It is limited by the small size of the compressor itself, and the fact that the compressor is considerably elevated above the stage. The other end of this compressor is a cork-filled disk revolver. This would be used to observe an opaque object. The disk can be rotated by its milled edge, and/or turned at an angle from the horizontal. This is similar to the Beck Disk Revolver, except that rotation of this device is directly with the fingers rather than via a knob communicating with the disk by a fusee chain. (From another Private Collection). Piper also had several other contributions to microscopy.

WENHAM TYPE:

compressor compressor The Wenham type, with its thinner profile, was said to be especially suitable for use with dark ground illumination, as when using a Paraboloid condenser. The top plate is threaded to accept the knob. The top plate is springy and when the knob is turned counterclockwise, the top plate is lowered on the object being studied.

FOREST TYPE:

compressor The Forest compressorium at first glance appears the same as the Wenham, but actually is the reverse, as tightening the knob moves the top plate down. In this case, the amount of pressure applied is not limited by the springiness of the top plate, since turning the knob applies the pressure and the springiness serves to keep the top plate off the subject when the knob is unscrewed.

GRAHAM TYPE (c. 1880):

grahamgraham 1880

HARDY TYPE:

compressorIn the early 1880's, Phin and also Hardy both described types of gravity compressor which was hinged on one end. This design was later modified and improved by Martin. The original description of this compressor is in both the JQMC and also the JRMS.

G. WATSON'S REVERSIBLE COMPRESSOR:

g. watsonThis compressor was noted in a brief note in the RMS Microscopical Journal, of 1886, page 520. Similar to the Piper instrument from 18 years earlier, its rotating parts are larger and therefore easier to handle, but a potential disadvantage is it requires a longer working distance to the objective when the subject holder is tilted. I would like to thank Dr Brian Stevenson for his kindness in supplying images of this compressor.

BULLOCH TYPE:

compressor This compressorium, supplied with microscopes made by Walter Bulloch, is similar to the Wenham type on one side, but also incorporates features similar(but not identical), to the Hardy on the other- an added feature of a second knob on the opposite side of the specimen so as to apply pressure to the top plate from that side if needed or to increase the parallelism of the arrangement.

DELAGE REVERSIBLE TYPE:

compressorThis compressor, devised by Professor Y. Delage in 1886 is similar to a Schieck-type lever compressor, except that instead of using a lever, a screw acts on a wedge attached to the top plate holder. This type of compressor was made by Nachet. Like Schiek's original design, it has three pins standing up from its surface, allowing it to be reversed on the stage.

GRAVITY COMPRESSOR WITH DIAMOND-SHAPED TOP PLATE (c. 4th Qtr of 19th C.):

comp This is a later version of the gravity compressor in its simplest form, as the compression is not adjustable and depends solely on the weight of the top plate. This design is not rare and examples exist in various collections including that of the Royal Microscopical Society. This example is signed 'REGD 244895.'   Although this number seems to date to 1870 in the British Registration database, it does not seem to correspond to this device.

ROUSELET TYPE (c. 1890's):

compressorrous This compressor was invented by Charles Rousselet, FRMS 'about 1890' and was first noted in the JRMS in 1893. The general pattern of the top plate riding on a post 90 degrees from the bottom plate and the shape of the top compressor plate is quite similar to that of the Ross Swing-out Compressorium Stage of many years earlier. In 1903, Cross & Cole stated in Modern Microscopy that this compressor was the best type then obtainable. (Also, see Rousselet, CF, A Description of the Rousselet Compressorium, JQMC vol IX, 1904-1906 p 137-140). This original design is far superior to the later modified designs (an example follows this entry), promulgated by various makers.

WATSON'S IMPROVED ROUSELET COMPRESSOR (c. after 1895):

Watson comprThis is one of the modified Rouselet compressors, which makers like Watson called their Improved version. These modified versions made some things like changing the glass easier while at the same time making them less useful by introducing factors which detract from the original design as can be seen in the more detailed page concerning this example by Watson. Rousselet himself suggested that the proper method of gluing the coverslip to the movable top plate was to apply a thin layer of Marine glue, let it dry for thirty minutes, and then apply the coverslip; the slip was warmed causing it to adhere to the Marine glue; the warming could also be used to remove the slip if it was broken. Using glue instead of just pressure to hold the coverslip in place eliminated the risk that oil from an oil immersion lens would leak into the fluid holding the specimen.

HIGH PRESSURE COMPRESSOR FOR DETECTING TRICHINOSIS (after 1870):

compr comprThis type of compressor came into widespread use about 1870 when Virchow convinced the German authorities that microscopical meat inspection was critically important in prevention of trichinosis. They continued to be used well into the twentieth century and large numbers of specialized and relatively inexpensive low power microscopes known as 'Trichinascopes' were produced especially in Germany. This example, from a model Vb trichinoscope, dates from the early 20th Century. In use a piece of meat (muscle) was teased out of the carcase with tweezers, placed between the two thick glass plates, and subjected to high pressure to make it relatively transparent. Low power was used to scan the meat and higher (medium) power was only needed to confirm what could be seen with low power. Today this process is different as the meat is digested with enzymes, allowing the larvae to sink to the bottom of the the solution and be more easily detected using a stereo microscope.

TAYLOR TYPE (4th Qtr 20th C.):

compressor The Taylor compressor is a modern version of the Rousselet.   It features high quality construction and stainless alloy components. It has a very fine thread adjustment allowing perfect adjustments for things like rotifers-just enough to slow them down without crushing them to death. It also features an 'isolation mechanism' so that as the compressor is tightened, the top plate is not rotated in any way. This may be the best compressor ever made for this kind of work. It was not intended for high pressure compression like a trichinoscope compressor. It was patented on May 17, 1988 by Howard L. Taylor of Sarasota, Florida who studied rotifers. I do not believe these are in production any longer.

The author would very much like to thank Dr. Joe Zeligs, James Solliday, Dr. Jurriaan de Groot and Dr. Brian Stevenson who were all kind enough to provide illustrations and offer very helpful suggestions for this page. Dr. Zeligs was also instrumental in helping me clarify some paragraphs.