Splices.= As the upper and lower chords have to be made in several
lengths, securely fastened to each other, and, in order to weaken the
built beam as little as possible, it is necessary to adopt some form
of splicing whereby the greatest amount of tensional strength may be
retained in the chord with the least amount of cutting, and yet have a
secure joint. Such a splice is shown in Pl. II, Fig. 4, and below is a
table from Vose's Hand-book, giving reliable dimensions.

Span. A C B B C D
Feet. Feet. Inches. Feet.
50 1.00 1-1/2 1.50
100 1.25 2 2.00
150 1.75 2-1/2 2.25
200 2.00 3 2.75

This manner of splicing requires the back of the splice block to be
let into the chord stick, against which it lies, about 3/4 of an inch.
To show how the various Engineers differ, as to their estimates of the
sizes of the several parts of bridges, I subjoin two Tables--one by
Prof. G.L. Vose, a well known Engineer, and one by Jno. C. Trautwine,
an Engineer of note also--and I would premise that a bridge built
according to either would be amply strong.

TABLE FOR DIMENSIONING A HOWE TRUSS BRIDGE.
G.L. VOSE.

End Centre Centre
Span. Rise. Panel. Chords. Braces. Braces. End Rods. Rods.
50 10 7 2--8 x 10 7 x 7 5 x 5 1--1-1/8 2--1
75 12 9 2--8 x 10 8 x 8 5 x 5 2--1-1/2 2--1
100 15 11 2--8 x 10 8 x 9 6 x 6 2--1-3/4 2--1
150 20 13 4--8 x 12 10 x 10 6 x 7 3--2 3--1
200 25 15 4--8 x 16 12 x 12 7 x 7 5--2 5--1

TABLE FOR DIMENSIONING A HOWE TRUSS BRIDGE.
JNO. C. TRAUTWINE, C.E.

| | |An Upper | A Lower | An End |A Centre| | End | Centre
Clear| | No.| Chord. | Chord. | Brace. | Brace.|Counter.| Rod. | Rod.
Span |Rise| of |---------|---------|---------|--------|--------|-----------|-----------
in | in |Pan-| No| | No| | No.| | No| | No| | No.| | No.|
feet.|feet|els.|Pcs|Size.|Pcs|Size.|Pcs.|Size|Pcs|Size|Pcs|Size|Rods|Size. |Rods|Size.
-----|----|----|---|-----|---|-----|----|----|---|----|---|----|----|------|----|-----
25 | 6 | 8 | 3 | 4x5 | 3 | 4x10| 2 |4x6 | 2 |5x5 | 1 |4x5 | 2 |1-5/16| 2 | 7/8
50 | 9 | 9 | 3 | 6x7 | 3 | 6x10| 2 |6x7 | 2 |5x6 | 1 |5x6 | 2 |