<p>Probably western red cedar, <em>thuja plicata</em>, especially if the observatory is in North America. Western red cedar is easily obtainable in North America. It has a light, red, wood that is particularly resistant to decay, and ideal for use in exposed positions.</p>

<blockquote>
  <p>The soft red-brown timber has a tight, straight grain and few knots. It is valued for its distinct appearance, aroma, and its high natural resistance to decay, being extensively used for outdoor construction in the form of posts, decking, shingles, and siding.[28] It is commonly used for the framing and longwood in lightweight sail boats and kayaks. In larger boats it is often used in sandwich construction between two layers of epoxy resin and/or fibreglass or similar products. Due to its light weight—390 to 400 kg/m3 (24 to 25 lb/cu ft) dried—it is about 30% lighter than common boat building woods, such as mahogany. For its weight it is quite strong but can be brittle.</p>
</blockquote>

<p><a href="https://en.wikipedia.org/wiki/Thuja_plicata" rel="nofollow noreferrer">Wikipedia: Thuja plicata</a></p>

<p>It may be worth pointing out that while "cedar" refers to a group of <a href="https://en.wikipedia.org/wiki/Cedar_wood" rel="nofollow noreferrer">Cedar woods</a>, trees of the proper <a href="https://en.wikipedia.org/wiki/Cedrus" rel="nofollow noreferrer">Cedrus</a> genus are rare and localized:</p>

<blockquote>
  <p>Cedrus (common English name cedar) is a genus of coniferous trees in the plant family Pinaceae. They are native to the mountains of the western Himalayas and the Mediterranean region, occurring at altitudes of 1,500–3,200 m in the Himalayas and 1,000–2,200 m in the Mediterranean.</p>
</blockquote>

<p><a href="https://en.wikipedia.org/wiki/Cedrus" rel="nofollow noreferrer">Wikipedia: Cedrus</a></p>

CC BY-SA 3.0
2017-11-12T02:49:52.073Z
Nice answer! Hope you don't mind the edit.
uhoh
CC BY-SA 3.0
2017-11-12T04:51:32.637Z
All improvements welcome!
Mick
CC BY-SA 3.0
2017-11-10T20:42:34.847Z
2017-11-12T02:49:40.387Z
2017-11-12T02:49:40.387Z
Mick
<p><a href="https://i.sstatic.net/GoPgW.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/GoPgW.jpg" alt="enter image description here"></a></p>

<p>I was told that it was "cedar", but that is an unclear term botanically.</p>

CC BY-SA 3.0
2017-11-10T17:47:40.007Z
*cedar.
What's unclear about it? Wikipedia has a good definition (https://en.wikipedia.org/wiki/Cedar) of the variety of woods called cedar. It would probably depend on where the observatory was located, although imported cedar is not out of the question.
Phil N DeBlanc
CC BY-SA 3.0
2017-11-10T20:09:35.440Z
@PhilNDeBlanc  What's unlear about the variety of woods called cedar is which tree or wood it is exactly, to paraphrase the question, or botanically, to refer to the question details.
Hannes
CC BY-SA 3.0
2017-11-11T04:15:40.190Z
As a chemist it seems highly unlikely that the wood would "absorb moisture" to any appreciable extent. I think Mick's answer is right in that cedar would be naturally more rot resistant than say pine.
MaxW
CC BY-SA 3.0
2017-11-11T10:13:03.643Z
@MaxW I do not think rot is likely on the inside of a copula that also contains delicate instruments, and thus would be taken care of. Still, some buffer to humidity might be useful. Maybe any wood would do, but the use of this red one seems to be quite consistent. When "The great Refractor" near Berlin was restored, they made an effort to obtain just this wood.
Hannes
CC BY-SA 3.0
2017-11-12T05:24:36.407Z
Do you think you could support your conjecture that *reddish wood was historically used inside observatory copulas, in order to absorb moisture?* While it sounds plausible, it would be better to show this is factual, and also more interesting :-) I'd love to see a reference to this.
uhoh
CC BY-SA 3.0
2017-11-12T17:39:28.993Z
@uhoh This was explained to me when visiting the historic Grosser Refractor in Potsdam (http://www.aip.de/highlight_archive/refraktor_einweihung/refraktor_0190_corr.jpg) , and also at an historic but active observatory in Bamberg, Germany. When they restored Grosser Refractor, they made some effort obtaining the correct wood. We dit not get past the "cedar" description though.
Hannes
CC BY-SA 3.0
2017-11-13T02:42:58.103Z
@HannesH Wow, the instrument, the observatory, and the cedar are all really beautiful! Since comments are supposed to be considered temporary (we can't at least rely on them being permanent) I wonder if you would consider adding something to the original question. There's a Wikipedia article (German) and a nice photo that could be included without concerns of copyright. Beautiful! https://commons.wikimedia.org/wiki/File:Great_Refractor_Potsdam.jpg and also https://de.wikipedia.org/wiki/Gro%C3%9Fer_Refraktor_(Potsdam) oh, also https://commons.wikimedia.org/wiki/File:Potsdam_Great_Refractor.jpg
uhoh
CC BY-SA 3.0
2017-12-25T05:31:33.283Z
I just noticed this article in the NYTimes contains a photograph of a wooden dome interior. Not sure if it's cedar. https://www.nytimes.com/2017/12/22/world/europe/vatican-observatory-consolmagno.html
uhoh
<history><observatory>
What kind of reddish wood is it exactly that was historically used to line the inside of observatory cupolas (domes), in order to absorb moisture?
Hannes
# What kind of reddish wood is it exactly that was historically used to line the inside of observatory cupolas (domes), in order to absorb moisture?

(Asked by: username_0 on 2017-11-10)

[![enter image description here](https://i.sstatic.net/GoPgW.jpg)](https://i.sstatic.net/GoPgW.jpg)

I was told that it was "cedar", but that is an unclear term botanically.

**Tags:** history, observatory
> **Comments:**
> **username_1**: *cedar. What's unclear about it? Wikipedia has a good definition (https://en.wikipedia.org/wiki/Cedar) of the variety of woods called cedar. It would probably depend on where the observatory was located, although imported cedar is not out of the question.  
> **username_0**: @PhilNDeBlanc  What's unlear about the variety of woods called cedar is which tree or wood it is exactly, to paraphrase the question, or botanically, to refer to the question details.  
> **username_2**: As a chemist it seems highly unlikely that the wood would "absorb moisture" to any appreciable extent. I think Mick's answer is right in that cedar would be naturally more rot resistant than say pine.  
> **username_0**: @MaxW I do not think rot is likely on the inside of a copula that also contains delicate instruments, and thus would be taken care of. Still, some buffer to humidity might be useful. Maybe any wood would do, but the use of this red one seems to be quite consistent. When "The great Refractor" near Berlin was restored, they made an effort to obtain just this wood.  
> **username_3**: Do you think you could support your conjecture that *reddish wood was historically used inside observatory copulas, in order to absorb moisture?* While it sounds plausible, it would be better to show this is factual, and also more interesting :-) I'd love to see a reference to this.  
> **username_0**: @uhoh This was explained to me when visiting the historic Grosser Refractor in Potsdam (http://www.aip.de/highlight_archive/refraktor_einweihung/refraktor_0190_corr.jpg) , and also at an historic but active observatory in Bamberg, Germany. When they restored Grosser Refractor, they made some effort obtaining the correct wood. We dit not get past the "cedar" description though.  
> **username_3**: @HannesH Wow, the instrument, the observatory, and the cedar are all really beautiful! Since comments are supposed to be considered temporary (we can't at least rely on them being permanent) I wonder if you would consider adding something to the original question. There's a Wikipedia article (German) and a nice photo that could be included without concerns of copyright. Beautiful! https://commons.wikimedia.org/wiki/File:Great_Refractor_Potsdam.jpg and also https://de.wikipedia.org/wiki/Gro%C3%9Fer_Refraktor_(Potsdam) oh, also https://commons.wikimedia.org/wiki/File:Potsdam_Great_Refractor.jpg  
> **username_3**: I just noticed this article in the NYTimes contains a photograph of a wooden dome interior. Not sure if it's cedar. https://www.nytimes.com/2017/12/22/world/europe/vatican-observatory-consolmagno.html  

---

## 1 answers

### Answer by username_4 on 2017-11-10. Score: 5

Probably western red cedar, *thuja plicata*, especially if the observatory is in North America. Western red cedar is easily obtainable in North America. It has a light, red, wood that is particularly resistant to decay, and ideal for use in exposed positions.

> The soft red-brown timber has a tight, straight grain and few knots. It is valued for its distinct appearance, aroma, and its high natural resistance to decay, being extensively used for outdoor construction in the form of posts, decking, shingles, and siding.[28] It is commonly used for the framing and longwood in lightweight sail boats and kayaks. In larger boats it is often used in sandwich construction between two layers of epoxy resin and/or fibreglass or similar products. Due to its light weight—390 to 400 kg/m3 (24 to 25 lb/cu ft) dried—it is about 30% lighter than common boat building woods, such as mahogany. For its weight it is quite strong but can be brittle.

[Wikipedia: Thuja plicata](https://en.wikipedia.org/wiki/Thuja_plicata)

It may be worth pointing out that while "cedar" refers to a group of [Cedar woods](https://en.wikipedia.org/wiki/Cedar_wood), trees of the proper [Cedrus](https://en.wikipedia.org/wiki/Cedrus) genus are rare and localized:

> Cedrus (common English name cedar) is a genus of coniferous trees in the plant family Pinaceae. They are native to the mountains of the western Himalayas and the Mediterranean region, occurring at altitudes of 1,500–3,200 m in the Himalayas and 1,000–2,200 m in the Mediterranean.

[Wikipedia: Cedrus](https://en.wikipedia.org/wiki/Cedrus)

> **Comments:**
> **username_3**: Nice answer! Hope you don't mind the edit.  
> **username_4**: All improvements welcome!  

---

