128 InscrisepD RomMAN STONES or DUMFRIESSHIRE. 
to Luguvallium (Carlisle), by way of Vzroconium (Wroxeter, lear 
Shrewsbury) and Zéduracum (York). From Luguvaliium it is con- 
tinued for 12 miles to Castra Lxploratorum (usually identified 
with Netherby), and for other 12 to Blatum Bulgium (appar- 
ently Birrens), where it stops. Another Iter, the First, also reaches 
the north on the other side of the island, and strikes the line of 
the Wall at Corstopitum (Corbridge, on the Tyne), whence it pro- 
ceeds to Bremenium (High Rochester), a distance of 20 miles. It 
deserves, however, to be noted that there is no mention of the 
Southern Wall or the stations on it, or of Hadbitancium (Rising- 
ham), a station nearly midway between Corstopztum and Bre- 
mentieme. 
We are on firmer ground when we pass on to inquire how 
early Birrens was a Roman station. A date is fixed for us by the 
tablet found in the pretorian buildings, which was set up there in 
the year A.D. 158, the twenty-first of the reign of Antoninus Pius. 
It does not, of course, follow that this was the year in which the 
station was either founded or completed. It may be so; but all 
that can be affirmed for certain is that it was then held in 
force by Roman auxiliary troops. The Disciplina altar certainly 
points back to the preceding emperor, Hadrian, whose regulations 
for all ranks in his army were exceedingly strict, and several of 
whose coins bear in consequence the legend, Désciplina Augustz. 
It is true that the same legend is found on some of the coins, 
probably early ones, of Pius. But this may be accounted for by 
the supposition that the severity which marked the discipline of 
Hadrian was continued by the heads of the army for years after 
his presence no longer inspired it. It is not so likely, however, 
that this severity would be singled out as an attribute of the mild 
Pius, specially worthy of adoration ; although this is possible. We 
may thus confidently place the erection of the altar between A.D. 
117 and A.D. 158. 
Whatever was the case in later times, Birrens appears to have 
been at first an advanced position, intended to guard the approach 
to the Southern or Lower Isthmus against the Caledonian foe. 
Its proximity to the line which Hadrian made the northern 
Limes of the Roman province of Britain, its resemblance in plan 
to Czlurnum (Chesters) and other stations on that boundary line, 
and its early date, all lead to this conclusion. Along with Castra 
Exploratorum it served the same purpose on the west as Hadzé- 
