Concerning the mixing up of shell-beds with the kitchen-middens of the Moa-hunters, there is no reason why the latter should not have been shell-eaters also; but all the undisturbed layers with Moa bones, seal bones, and ashes, which I examined carefully at different levels, never contained any shells, and the undisturbed shell-beds did not contain any Moa bones. However, in many localities, owing to the shifting nature of the sands, I observed that the contents of the older and newer beds had very often become mixed. This was exhibited very clearly in one spot, where a small hillock, with a layer of ashes, stones, and Moa bones, had partly become destroyed, the contents of the layer rolling down and covering a bed of shells lying in the hollow between the sand-hills.
As such a destruction and mixing of beds belonging to different periods have been going on for a long time, it is evident that if, as in this case, the re-arranged beds have been mistaken for original ones, it simply proves that the excavators possessed insufficient experience to distinguish between them.
On a new Fire-grate for economising the Combustion of Coals and Lignites, and increasing the Radiation of Heat. By H. Skey.
[Read before the Otago Institute, 4th July, 1876.]
In a former paper read before this Institute, a method was described by which coal and lignite could be consumed without wasting the heat contained in the column of air which ordinarily passes up the shaft of the furnace of the steam-engine, and in the discussion which arose thereon the desirability was suggested of devising some method by which the combustion of brown coal and lignite could be rendered more perfect in open fires and sitting-room grates. The use of a blast for this purpose would be scarcely applicable, as it would require special machinery for each fire-place.
Experiments were, however, undertaken last year, on the combustion of these fuels in an open grate, the final result of which is exhibited in action, as I have been kindly allowed to substitute one of these grates in the fireplace of this room for the evening. The fuel used is from the Green Island mines. It is well known that stirring these fuels makes them burn worse, also that a great vertical thickness is injurious to their combustion, as the superincumbent weight crushes the fuel, so that scarcely enough heat is generated to sufficiently warm the chimney to ensure the passage of the liberated smoke and gases up the flue. For these reasons, the attempts to burn them in grates specially constructed for hard and bituminous coals, leads to anything but a cheerful result.
