Brarr.—On the Building Materials of Otago. 119 
nouncing it the best lime for building purposes hitherto discovered in North 
Otago. It is very much superior to the lime in common use from the 
Kakanui kilns. 
All the other Otago limestones in Table III. are from the Peninsula and 
Lower Harbour Districts ; they seem to be members of one large deposit 
that extends from Seal Point, on the southern side of the Peninsula, to 
Dowling Bay, on the northern shore of the Lower Harbour. It is near the 
surface from the ridge south of Mr. Macdonald’s kilns to the gully at 
Harbour Cone; appears again at the head of Hooper's Inlet, and for the 
last time on Mr. Dodson's property in Dowling Bay, right across the 
harbour. The breadth of this reef or dyke is unknown; probably it is not 
more than half a mile, and the aggregate thickness of the seams now visible 
is at least 70 feet. There are five or six distinct beds of varying quality 
and depth ; as a rule they are well defined, particularly near the upper and 
lower sides, but occasionally more than one kind of stone is found in the 
same stratum. Mr. Macdonald, of the Peninsula kilns (the highest on the 
reef), only eounts four beds, while Mr. Robertson, of the Glenmore kilns 
(which are situated on a much lower level), shows six tolerably distinct 
specimens from as many different layers. Two of them are, however, so 
thin that they can scarcely be called beds, and it is also quite possible that - 
they exist in a less marked degree in the upper quarry. There are five 
well defined seams at Dowling Bay, four of which have been analyzed, viz. 
—one, two, three, and five, counting from the top. The fourth, which is 
20 feet thick, was partially analyzed, but, being found to contain 28:18 per 
cent. of sand, it was useless to proceed further. Whether regarded as to 
structure, consistency, general appearance, or chemical composition, these 
Otago rocks exhibit all the peculiarities of hydraulic limestones of no mean 
order. Still, as the best authorities recommend a practical test also, I 
applied it, and the result is equally satisfactory. Mr. Macdonald, at my 
request, kindly burned samples of what I considered hydraulic stone. As 
was expected, the lime would not slake in the usual way, and it was pul- 
verized by grinding in a chaff-cutter and sifting through acloth. In conse- 
quence of other engagements I could not complete the experiments at that 
time, so the lime lay for eight months in a state of powder, which is not 
calculated to improve its setting properties. There happens to be a parcel 
of English blue Lias lime at present in Dunedin, so I tested it and the 
ordinary rich kind from Waihola along with the hydraulic sample from the 
Peninsula. All the three kinds were submitted to the same treatment and 
tested together. They were made into mortar neat, and with a mixture of 
two parts of sand ; one set was left to dry in the air, and the other placed 
at once in water. So far as could be determined by mere inspection, the 
action of the indurating process was parallel in the English and Peninsula 
