Year/Period |
1870-1890 |
Maker |
CROUCH |
Country |
United Kingdom |
Signature |
Henry Crouch / London / 7353 |
Category |
Microscopes |
Optical 1 |
Compound |
Optical 2 |
Achromatic |
Size of the box (h x w x d) |
15.6 × 30.8 × 18.7 cm |
Size of the microscope (h x w x d) |
29 × 13.8 × 18 cm |
Inventory number |
SM 7 |
In box with lock.
This is a simpler version of the microscope described under SM 5, coarse adjustment is only by means of a sliding tube in a sleeve. Fine adjustment is by a micrometer screw acting on the limb.
There is one Huygenian eyepiece, its focal length is 27.8 mm, its magnification is 9×.
There are two objectives, ‘2/3’ and ‚1/6’, provided with the standard RMS thread. Both were investigated using the Bleeker microscope with a 160 mm body tube and a 5× Huygenian eyepiece.
| Objective lens | 2/3 | 1/6 |
| Focal length (mm) | 15.57 | 3.55 |
| Magnification | 47.7 | 243 |
| Numerical aperture | 0.15 | 0.64 |
| Resolving power (µm) | 2.5 | < 0.8 |
Objective ‘2/3’ is still in good condition, the results of the star test are good, even its contrast is well defined. Objective ‘1/6’ is not in such a good condition anymore, there is a fault in the cement between two of its lenses. As a result the contrast of the image is not very good and the diffraction rings are not circular. With a Möller diatom test the image is a bit hazy. Stauroneis phoenicenteron is resolved into dots, it is possible that the objective could resolve Pleurosigma angulatum as well when in good condition.
See also SM 5.
info@stichtinghistorischemicroscopie.nl
Visseringlaan 25
2288 ER Rijswijk
The Netherlands
RSIN: 804217361
KVK: 41182753
IBAN: NL53INGB0007728414
The Historical Microscopy Foundation is independent and non-commercial. Your support is vital to enable the Foundation to fulfil its mission and to guarantee its continuity. We are very grateful for all financial contributions, as well as donations of progress objects for the collection.
Donate
