McARTHUR PORTABLE COMPOUND MICROSCOPE

 

This instrument came complete with many accessories including:

Additional accessories were offered by CTS. These included three different types of inserts for the illuminator which took the place of the battery, and by wire, attached to external power sources. The types of inserts included a simple insert which simply hooked up to external power, an insert with fixed resistance, dropping 3 volts down to two, and a variable resistance insert with a small knurled knob at its rear to vary the voltage. The body of these needed to be nonconductive, so they were all made of Ebonite, except for the electrically conducting parts. All these were the size of the battery normally used (AA). Besides the standard achromatic objectives, flourite objectives and special purpose-made condensers for use with them were also offered. Three different carrying cases were available; these included the Perspex case seen with my microscope, and two different leather cases, the slightly larger one allowing the microscope with its illuminator to fit inside. A matching belt to carry the instrument on the waist was also available. The larger leather case can be seen with an example of Dr Goren's microscope here. As noted above, and shown in the image below, using the illuminator attached to the footplate, and changing the standard optical prism tube to a beam-splitting tube, incident illumination of opaque objects could be accomplished. There were at least three prismatic light tubes available, the standard, an erecting light tube allowing easier use for e.g. dissection, and a beam-splitting or photo optical tube allowing incident illumination and photography. The standard tube gives appropriate up and down views but right to left movement is seen reversed in the eyepiece.

The objective plate holds the three brightfield objectives, all signed 'Cooke. The low power has the additional engravings '87417 16 mm achro 0.2 NA.' The 40X has the serial number 91244 and also engraved '40X, 0.85'. The 100X has the serial number 91839 and is also engraved '100X, 1.3 OIL. Only the low power objective is knurled. These are the original objectives, and correspond exactly to the labelling on the original box. Although a phase contrast condenser is present, no phase contrast objectives are currently with this outfit. It should be noted that the objective plate supplied with the Kirk-McArthur does fit the dovetail in the Cooke-McArthur, but the fit is not as exact as the original Cooke objective plate, being slightly narrower. I have recently been able to add lying drop slides obtained in 2013 from Burwell engineering in Cambridge, UK. I have discovered that the fittings on the end of the stage clips which make contact with the slide are tender and break if bent; to increase the tension of the stage clips, the clips should be bent further in their middle rather than the end if increased tension is required!

HISTORY: This is the Cooke, Troughton and Simms (CTS) version of the famous McArthur microscope, called the Cooke-McArthur model. It incorportates almost all of the improvements made in the design. The quality and precision of the instrument are really quite impressive. CTS was a subdivision of Vickers Ltd; after Vickers Ltd became Vickers Instruments (about 1962-3), the microscope label changed to 'Made by Vickers Instruments in England M130553.' To the best of my knowlege, there is no difference between the CTS model and the Vickers model, other than the signatures (see Dr Goren's Vickers Model here). The patent, filed in 1959, addresses the bottom plate and the use of pins to attach the mirror or the illuminator to the condenser arm. For much more on the history of the McArthur microscope, please see my McArthur Main page.