TflE EOYAL AETILLEEY INSTITUTION. 
39 
any point pass through- -the whole circuit in such a manner that" Quintus ” 
communicates, simultaneously with all the forts and batteries, and the 
messages exchanged among any of them pass at the same time through all 
the other stations. 
A special apparatus established at Cf Quintus ” affords the means of 
separating the stations into several independent groups all however com¬ 
municating with the principal station, an arrangement which would be very 
useful in the case for example of a combined attack on both north and south 
forts, for "Quintus” could then correspond at the same moment with the 
northern group ("Huth,” "Ny Kalkbrsenderi ”) the southern (" Provesteen,” 
“ Mellemfort,” " Strieker ”), and besides with the principal forts of (" Trek- 
roner, “ Lynetten,” and " Provesteen,”) which are for this purpose provided 
each with two sets of receiving apparatus. 
The telegraph apparatus employed at each station is the Morse receiver 
without relays, recording in ink, and made by Digney Brothers and Co., 
Paris. 
The galvanic batteries are as weak as possible, being composed of only 12 
cells, so that the resistance to the electro-magnets, as I am assured by direct 
experiment, is only one-seventh of the ordinary resistance, or about 200 
units of Sieman’s scale for each receiver. 
The operators were young soldiers selected for the purpose, who during 
the establishment of the telegraphic communication were thoroughly instructed 
in all telegraphic operations. 
Measurement of Distances. 
On each fort or battery there is a covered observatory in such a position 
as to command a good view of the horizon, and when its distance from the 
telegraphic operator is great enough to render it necessary, means of instant 
communication are afforded by an acoustic tube. The measurement of 
angles from the observatory is effected by a theodolite the telescope of which 
is short and field of vision large. The horizontal circle is provided with a 
Vernier, which allows of angles to every 5' being read off easily and quickly. 
According to my original plan, the measurement of distances was to have 
been effected by means of tables giving the distances corresponding to observed 
angles. But during the preliminary labours of the commission, the chief 
engineer Major Ernst, proposed a graphical method which he considered 
Would afford results of sufficient accuracy for artillery purposes provided 
that the maps or charts employed were on a sufficiently large scale, and this 
idea having been approved, each station was provided instead of tables with 
a chart embracing a distance from the fortifications of about fths of a mile 
(6 kilometres). These charts are on a scale of Tvim ail( ^ are spread each 
upon a table. Upon each of the forts and batteries indicated on the charts, 
and in a position corresponding exactly to the centre of each theodolite a 
small brass circle is fixed carrying a very fine black thread and surrounded 
by a concentric exterior circle, divided into degrees and twelfths of degrees, 
the zero point of which is in the north. 
Before commencing observations all the theodolites as well as the divided 
circles on the charts are adjusted, so that the zero points may all be exactly 
in the north. ' 
