Heller and Brightly.] 1 I 6 [May 5th, 
one inside of the other, and neither of them being exposed or detached 
from the instrument, thus remedying the two last causes of error. These 
two are the only styles of Transit made, and are respectively termed the 
“short centre Transit’? and the ‘‘long centre Transit.’? The ‘long 
centre,’’ although the most perfect in its construction, has never been a 
favorite among Railroad Engineers for the following reasons : 
ist. The increased size of the centres making it heavier, and this being 
a very serious objection where an instrument must be carried several 
miles every day as is frequent in Railroad surveys. 
2d. The instrument not being detached from the tripod, except at the 
base, compelled the Engineer in moving the instrument from one station to 
another to either carry the entire instrument himself or trust it to his assist- 
ant, while in the short centre, the instrument lifting off the spindle, the 
Engineer could take the comparitively light instrument with all the im- 
portant parts, and leave his assistant to carry the heavier portion of the 
tripod with its leveling screws, legs, etc. 
3d. The removing and replacing of the instrument on the tripod being 
accomplished by means of a large screw thread, is a very tedious and un- 
safe method, and if not very carefully performed is liable to injure the 
instrument. 
Ath. The extra skill, time, and care required in making the long centre 
was so much greater than the flat centre, that the price of the instrument 
was materially increased. 
Ever since the introduction of the Transit numerous endeavors have 
been made to reduce the weight of the instrument, but as they have all 
been conducted on the same principle, 7. ¢., reducing the thickness of the 
various plates, etc., their only effect was to make the instrument so slight 
as to be unsteady, their bearing surface so short as to soon wear loose, 
and the instrument always losing its adjustment. The manufacturers of 
this instrument have had their attention drawn to the increased strength 
and steadiness that the employment of the ‘‘transverse section,’’ ‘ rib- 
bing or bracing,’ imparted to metals; and the amount of metal that 
could be removed from a solid plate of metal, and its strength and steadi- 
ness not impaired, but even added to, if only judicious ribbing was re- 
sorted to. In this improved Transit, which is a long centre, the weight 
as compared with an ordinary Transit of the same size is reduced one-half, 
and the instrument is not contracted in any part, but insome parts where 
increased size would be an advantage, such as the graduated plate, centre, 
etc., it has been done, but all the plates, etc., are ribbed in such a way as 
to be stronger than a solid plate, and all metal that did not impart 
either strength or steadiness has been removed. 
The Railroad Engineer has in this instrument along centre Transit 
that can be taken from off the tripod and replaced in a quicker and surer 
