I couldn't find 24 B 61 in the AISC database. What's the depth of the beam? Is it 24" or 27"? According to AISC "B" is a Carnegie beam; I looked in an old Carnegie Steel manual cicra 1920 and they have two ways of designating beams, one is called "Section Index". I found a 27" beam at 90 #/LF that was designated as "B61". The properties are posted below:
Library: HISTORIC
Type: ALL (Depth)
ID = 54
Designation = B61
W = 90
A = 26.34
D = 27
TW = 0.524
BF = 9
TF = 0.708
T = 24.306
K = 1.347
BF_2TF = 6.36
H_TW = 46.4
FY3P = 30
X1 = 1860
X2 = 17103
IX = 2958.3
ZX = 253.1
SX = 219.1
RX = 10.6
IY = 75.3
ZY = 28.1
SY = 16.7
RY = 1.69
J = 3.93
CW = 13014
a = 92.6
WNO = 59.2
SW = 94
QF = 39.4
QW = 127
FSTR = C 1916,C 1917,C 1919,C 1920,C 1921,C 1923,