Interesting Slide!

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Element 56
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Interesting Slide!

#1 Post by Element 56 » Thu Jun 18, 2020 8:10 pm

Hello,
I got a new specimen cabinet and while organizing my collection I found this odd slide. Is this just a manufacturing error or is there some purpose to mounting a specimen on a tapered slide?
IMG_18062020_113106_(400_x_600_pixel)_2.jpg
IMG_18062020_113106_(400_x_600_pixel)_2.jpg (28.63 KiB) Viewed 4881 times
IMG_18062020_113226_(400_x_600_pixel)_2.jpg
IMG_18062020_113226_(400_x_600_pixel)_2.jpg (53.14 KiB) Viewed 4881 times
Thanks,
Kirby

Charles
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Re: Interesting Slide!

#2 Post by Charles » Sat Jun 20, 2020 5:22 pm

That is unusual. I've never seen a slide like that. I don't see how the taper would help with view that specimen. It would make it more difficult to view because you would be constantly trying to get it in focus. Probably just a defect in that slide.

Element 56
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Location: Lancaster County, PA

Re: Interesting Slide!

#3 Post by Element 56 » Mon Jun 22, 2020 3:12 pm

Hi Charles,

Thanks for commenting.

I kind of wondered if it was created as a test of some sort but I have no idea what that could be. Otherwise I see no obvious explanation other than a mistake. Seems strange that someone would miss that during mounting but I'm certainly not exempt from such foul up!

Kirby

MicroBob
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Re: Interesting Slide!

#4 Post by MicroBob » Mon Jun 22, 2020 3:22 pm

For me this is an interesting problem from the manucafturing side: How was this glass made? With todays float glass it is probably difficult to get such a taper. Our house is 75 years old (material perhaps a lot older) and some of the old window panes showed some interesting irregularities that are not found on today's glass.

Do you have the means to test the two surfaces for evenness?

hans
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Re: Interesting Slide!

#5 Post by hans » Mon Jun 22, 2020 6:25 pm

Element 56 wrote:
Mon Jun 22, 2020 3:12 pm
Seems strange that someone would miss that during mounting ...
Seems like it could be intentional, not for any optical reason, but to save money. Maybe someone bought some defective/rejected slides at a discount? Or the manufacturer donated them to the university for students to practice on?

Element 56
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Re: Interesting Slide!

#6 Post by Element 56 » Mon Jun 22, 2020 6:31 pm

Hi Bob!
MicroBob wrote:
Mon Jun 22, 2020 3:22 pm
For me this is an interesting problem from the manucafturing side: How was this glass made? With todays float glass it is probably difficult to get such a taper. Our house is 75 years old (material perhaps a lot older) and some of the old window panes showed some interesting irregularities that are not found on today's glass.
I have replaced some windows in old farm houses with that not so clear glass. Some of it is pretty bad! I wonder if they used the Fourcault process to make microscope slides

MicroBob wrote:
Mon Jun 22, 2020 3:22 pm
Do you have the means to test the two surfaces for evenness?
Yes, I can check it with my surface gauge! Now I just need to remember which drawer I put the slide in!

Kirby

Zuul
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Re: Interesting Slide!

#7 Post by Zuul » Tue Jun 23, 2020 12:36 am

I don’t pretend to have any idea why it was made that way, but I can’t imagine that is was accidental. The taper is too pronounced to be overlooked.

MichaelG.
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Re: Interesting Slide!

#8 Post by MichaelG. » Tue Jun 23, 2020 5:59 am

Element 56 wrote:
Thu Jun 18, 2020 8:10 pm
Hello,
I got a new specimen cabinet and while organizing my collection I found this odd slide. Is this just a manufacturing error or is there some purpose to mounting a specimen on a tapered slide?
.

I have an idea, Kirby [but no substantiating evidence]
... I am no histologist, so this might be nonsense; but here goes:

The specimen is one in which surface details are significant, and would be best viewed ‘without coverslip’ ... but is here presented as a mounted slide [perhaps as a reference sample].
acute nephritis, kidney, exudative type
Axial incident lighting would be reflected from the coverslip, causing flare.
... This can be mitigated by tilting the slide, to divert the reflection.

So: make the slide wedge shaped, to achieve the same effect with the slide correctly located on the stage.

MichaelG.
Last edited by MichaelG. on Tue Jun 23, 2020 6:07 am, edited 1 time in total.
Too many 'projects'

MicroBob
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Re: Interesting Slide!

#9 Post by MicroBob » Tue Jun 23, 2020 6:04 am

Depending on the process there might have been a small percentage of really good slides and a lot of ones of barely usable quality. For economic reasons they may have been used it at all possible. I think I read that old slides also varied in thickness a lot, which would be a problem for high power dark field use.

Element 56
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Re: Interesting Slide!

#10 Post by Element 56 » Tue Jun 23, 2020 8:32 pm

Some interesting thoughts! Thank you all for commenting.

I did check it with my surface gauge and it is uneven. The tapper is about .040" across the length which is pretty extreme. There is about a .005" deviation across the width on both ends and the slide does not lay flat against the surface plate. It kind of rocks side to side which makes me thing it was just a dud!

I should, just for fun, check some of the other slides from that lot to see what there tolerances are. As someone mentioned I find the thicknesses vary with my older slides. I have some that don't fit between the slots on modern slide boxes. A good reason to keep those old wood ones around!

Kirby

dtsh
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Re: Interesting Slide!

#11 Post by dtsh » Wed Jun 24, 2020 3:51 am

That it doesn't even lay flat is what stands out most to me, talk about bad quality control.

MicroBob
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Re: Interesting Slide!

#12 Post by MicroBob » Wed Jun 24, 2020 6:25 am

I think it is very unlikely that a production process delivers perfect flat 1mm slides all day and then this one. So it is probably the result of a much more limited production process, probably hand made from a blown ball of glass, flattened, stetched out, cut to pieces. It probably is really old, 150 years or so, and a nice collectible and discussion topic.

PeteM
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Re: Interesting Slide!

#13 Post by PeteM » Wed Jun 24, 2020 6:53 am

Bob, I think you're on to something - the Columbia College of Physicians and Surgeons was founded in 1767. Can't tell from the photo, Kirby, is there a date on the slide as well as the college name?

https://www.ps.columbia.edu/about-us/hi ... d-surgeons

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75RR
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Re: Interesting Slide!

#14 Post by 75RR » Wed Jun 24, 2020 7:15 am

Can't tell from the photo, Kirby, is there a date on the slide as well as the college name?
Looks like 19th of March 1911 ... I don't suppose it could be 19th of March 1811?
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)

MichaelG.
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Re: Interesting Slide!

#15 Post by MichaelG. » Wed Jun 24, 2020 8:36 am

The owner of this site : http://www.victorianmicroscopeslides.com/slide1840.htm
would probably be interested, and may be able to advise.

MichaelG.

.

P.S. ___ this annotation to a rather effective image may give some credence to my earlier suggestion:
Injected and corroded kidney section showing structures (combination transmitted and reflected lighting).
.
Ref. http://www.victorianmicroscopeslides.com/slidehis.htm
Too many 'projects'

Element 56
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Re: Interesting Slide!

#16 Post by Element 56 » Thu Jun 25, 2020 7:15 pm

Hi,

I'm no expert on antique slides but I'm pretty sure slide is from 1911 for two reasons. First in my experience the label is indicative of the 1890's to maybe the late 1920's. Second is the size of the slide. This is not definitive by any means but if my memory serves me around 1835 is when this size started showing up. Please don't take any of that as historically accurate. It is just my observations from my collection and going from my memory, information I may have read somewhere. I will add that after collecting slides for a while one starts to get a "feel" for the time frame they were made and this one feels 1900's to me! :mrgreen:
MichaelG. wrote:
Wed Jun 24, 2020 8:36 am
The owner of this site : http://www.victorianmicroscopeslides.com/slide1840.htm
would probably be interested, and may be able to advise.

MichaelG.


Michael,

That's a great idea! I will do that and report back.
dtsh wrote:
Wed Jun 24, 2020 3:51 am
That it doesn't even lay flat is what stands out most to me, talk about bad quality control.
Some of the other slides in the collection do exhibit some unevenness.
PeteM wrote:
Wed Jun 24, 2020 6:53 am
Bob, I think you're on to something - the Columbia College of Physicians and Surgeons was founded in 1767. Can't tell from the photo, Kirby, is there a date on the slide as well as the college name?
This as well as others in the collection are marked Coll. Phys. & Surg. Columbia Univ. NY. Most are mounter marked "MH" and some also say H+P.A.F. I have to dig thought them again but I think one even had a patient's full name on it!

Thank you all for your thoughts on this and by all means please continue to share. I really appreciate it!

Kirby

Element 56
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Location: Lancaster County, PA

Re: Interesting Slide!

#17 Post by Element 56 » Thu Jul 09, 2020 2:46 pm

As suggested I asked the owner of the Victorian microscope slide site, http://www.victorianmicroscopeslides.com/history.htm and he very kindly replied with his thoughts. He felt that the slide was just a defect. Since it was made by medical students it suited it's purpose and ultimately would not have had any negative effect when viewing. He added that the standard non-plan objectives of the period regularly required refocusing so one may not even noticed the tapper. Regarding the date he agreed it's definitely from 1911. He added, "Another obvious reason is the thin sectioning and staining used, which looks to be haematoxylin and eosin (H&E), as this protocol was only first introduced in 1876." I thought that last part was very interesting and valuable information for dating similar slides.

Thanks to all who shared thoughts on this!

Best Regards,
Kirby

Voyager-1
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Re: Interesting Slide!

#18 Post by Voyager-1 » Tue May 04, 2021 11:47 pm

Element56,
Found the discussion quite interesting.
Have you tried putting the slide between two polarizers to see if it is a wave/retarder plate?
Back in the late 1800's Jacques Babinet was already using compensators.
Here is Wikipedia's entry, paragraph 3 discusses his wedges of quartz.
Just wondering if a student might have mounted the specimen on a wedge????
Would be interested if you notice any birefringence or phase shifting.

https://en.wikipedia.org/wiki/Jacques_Babinet

One way or another let us know what you see!

V

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