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Though Jocelyn’s legend tells us nothing of the causeway or hurdle 
road over the ford leading to Dublin city from Ath-cliath, yet his usage 
of this name in relation only to the village on the north side of the 
Liffey is pregnant with valuable topographical information, and helps 
to get us over certain engineering difficulties in which the question of an 
approach from the north to the city of Dublin was involved. 
Everybody can understand what use a hurdle bridge would have 
been if over the low land, which could at certain times be forded or 
waded by passengers up to the deep bed of the river. Jocelyn’s legend 
tells us nothing directly of the shallowness of the tide water from Ath- 
cliath to the bed of the river, but we know that must have been a fact, 
from the relation of other facts to this, and of this to others, so there can 
be no doubt about it. Neither does he tell us anything directly about 
the depth of the river close to the city, or of the force of the retiring 
tide after leaving the flooded lands above that point on the south bank 
of the Liffey, above which we cannot suppose the buildings of ancient 
Dublin to have ever extended. This point is evidently indicated by the 
old Bridge at the end of old Bridge-street. But both the returning tide 
and its great force, from the vastly greater quantity of water which in 
those times must have passed up and downwards in the same time that 
it passes now, when so much low ground is reclaimed, are indicated by cer- 
tain events mentioned in the legend, as to the cause of the drowning of 
the daughter of the King of Dublin, and the drifting of her body to sea 
by the current. 
So that, im one way or another, the number of direct and indirect 
facts and incidents which exist in Jocelyn’s legend exhibit the most dis- 
tinct knowledge of the topography of ancient Dublin in the twelfth cen- 
tury, or earlier. And, from the statements in favour of the northern well 
having been the original well of St. Patrick, it looks as if the original 
writer of the legend, whether he were Jocelyn or not, had belonged to 
Mary’s Abbey, or to some other of the old religious foundations on the 
north side of the Liffey ; and so he told the legend, to cover, at least, a 
claim to the well on his side of the river and its waters, to be as good, if 
not much better, for domestic purposes, than that of the southern well 
of St. Patrick,—a claim which we are disposed to grant, if the water 
of Mr. Carton’s pump, in Halston-street, be so much better than the 
water of the southern or famous well of St. Patrick, which we believe 
it is, because it is used for a vast variety of purposes, for which the 
spring well water of the neighbourhood of Nassau-street is not fit. 
The northern well is now accessible by means of a fine flight of 
steps, which also lead into a large vaulted chamber or crypt, which lies 
east and west; and though now, to a great extent, filled up with old 
sawdust, and timber here stored, has clearly a church character in the 
semicircular arching of the roof, and the careful finishing of the openings 
in the roof, to admit light and air, and also in the lateral arches which 
lead off right and left, like chapels. 
