Heliograph 3-inch Mark I - latch detail : 無料・フリー素材/写真
Heliograph 3-inch Mark I - latch detail / signal mirror
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
|---|---|
| 説明 | This shows the closed latch on the hinged sighting arm of a Mance Heliograph 3-inch Mark I, as a side view and a detailed side viewA heliograph is a signaling instrument using flashes of sunlight reflected by a mirror[1]. The Mance heliograph[2] saw military use from the 1870s to the 1960s, and most had 5" mirrors, though 3", 8" and 10" models were also used[3]. One popular use of the smaller heliographs was for cavalry.While Mance 3" heliographs were in manufacture by 1889[3], the first order in the "List of Changes War Material - Heliograph" that mentions[4] them isparagraph §10337 (Order 4 Jul 1900, published in LOC Nov 1900) definingthe "Heliograph (Mark I.) 3-inch" saying they are "similar to the 'Heliograph, 5-inch, Mark III.' (§1030), except the dimensions are correspondingly smaller."I believe this is a Heliograph 3" Mark I, because it lacks some of thechanges in the Heliograph 3" Mark II definition in "List of Changes War Material - Heliograph" paragraph §12167 (Order 12 Dec 1902, published in LOC May 1904),specifically:(1.) Change the sighting arm to straight (vs. hinged, as here) ...(5.) The mirrors are inserted from the front, and not from the back of the mirror frames (note the screw heads around the mirror here are at the mirror back, not the front)[1] en.wikipedia.org/wiki/Heliograph[2] www.prc68.com/I/MkVHeliograph.shtml[3] flic.kr/p/QUaV9S [https://www.flickr.com/photos/signalmirror/32095517470][4] Thanks to Ross Torrington for the "List of Changes" information. Ross has some interesting heliograph equipment photos on Flickr, here: www.flickr.com/photos/188484776@N05/ |
| 撮影日 | 2020-10-25 17:55:58 |
| 撮影者 | signal mirror |
| タグ | |
| 撮影地 | |
| カメラ | DSC-RX100M2 , SONY |
| 露出 | 0.01 sec (1/100) |
| 開放F値 | f/3.2 |