Spanish term (edited): mira estadimétrica

I'm not completely sure which is a more accurate term to call them.
I think "stadimetric reticle" is exactly la "mira" del instrumento, but the term itself is more used in weapons and it's the specific part of the instrument http://www.ogleo.com/search/encyclopedia-Reticle (but it might just be called the same in other areas).

I'd rather think of the instrument as a whole,that is / stadia measuring telescope / stadi(a)metric telescope or rangefinder.

[...] Stadia is a technique of measuring distances with a telescopic instrument. The term stadia comes from a Greek unit of length.

Stadia readings, used in surveying, can be taken with today’s modern instruments such as transits, theodolites, and levels. When using the stadia measuring method, a measurement rod is held so that it appears between two stadia lines visible on the instrument's reticle. A transit or level equipped for stadia work has two additional horizontal cross wires spaced equidistant from the center of the telescope. The interval between stadia wires in most stadia instruments gives a vertical ratio of 1:100. The distance to a rod can be read directly simply by multiplying the rod measurement between the stadia hairs by 100. This system is sufficiently precise for locating topographic details such as rivers, bridges, buildings, and roads to a reasonable accuracy.

The stadia method is based upon the principle that in similar triangles homologous sides are proportional. The stadia method is good when accuracy of 1/400 is acceptable. In a transit there are 3 horizontal wires and 1 vertical wire. The center horizontal wire is used for normal sights. The top and bottom wires are the stadia lines. The principle is relatively simple, at a distance of 100 feet the difference between the top and bottom wires on the rod is 1 foot. The transit or level must be horizontal for this formula to work.[...]
http://www.ogleo.com/search/encyclopedia-Stadiametric_rangef...

The transit refers to a specialized type of theodolite that was developed in the early 19th century. It featured a telescope that could "flop over" ("transit the scope") to allow easy back-sighting and doubling of angles for error reduction. Some transit instruments were capable of reading angles directly to thirty arc-seconds. In the middle of the 20th century, transits came to be known as a simple form of theodolite with less precision, lacking features such as scale magnification and mechanical meters. The importance of transits is waning since compact, accurate electronic theodolites have become widespread tools, but transits still find use as a lightweight tool for construction sites. Some transits do not measure vertical angles.
http://en.wikipedia.org/wiki/Transit_(surveying)


STADIMETRIC TELESCOPE
STADIMETRIC TELESCOPE. ... Modern Translation: STADIMETRIC TELESCOPE. Language, Translations for "STADIMETRIC TELESCOPE"; alternative meanings/domain in ...
http://www.websters-online-dictionary.org/definition/english...

Crosshairs and numbers in the manual binocular [Archive ...
the "crosshair" is called reticle, and the whole assembly of lines and numbers, is called stadiametric lines. the GAS itself is a stadiametric telescope. ...
http://www.steelbeasts.com/sbforums/archive/index.php/t-7499...

An explanation also appears for the term in French in Kudoz, too.
http://www.proz.com/kudoz/772982

Hope it helps!

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Note added at 2 hrs (2007-04-08 04:45:20 GMT)
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Sorry, forgot TRANSIT on the title, but I think it might be too old...

Here are some photos

http://images.google.com/images?hl=en&q=TRANSIT level&btnG=S...

http://images.google.com/images?hl=en&q=Transit surveying&bt...