In the present case the subject of the demise to the appellant by the dredging leases was "portion of the surface of the seabed as exists from time to time", and soil below the surface, but not including water or air space above the surface of the seabed, except such as was occupied by "any improvements", i.e. by the navigational aids. It was held by Mason J. in Goldsworthy Mining Ltd. v. Federal Commissioner of Taxation [19] that each dredging lease was a lease of land, and the decision of the Full Court by which his judgment was affirmed proceeded on the assumption that the seabed was land the subject of the leases [20] . The first question that then arises is whether when the appellant dredged the seabed it could be said to have effected an improvement upon the seabed. In Goldsworthy Mining Ltd. v. Federal Commissioner of Taxation [21] , Mason J. considered that this question should be answered in the affirmative, but I doubted whether that view was correct although I did not find it necessary to decide the question [22] . Having reconsidered the matter, I have reached the conclusion that the work done in dredging the channel did not effect an improvement upon the seabed. An improvement on land is an operation done on land which has the effect of enhancing its value: Morrison v. Federal Commissioner of Land Tax [1] ; Brisbane City Council v. Valuer-General (Q.) [2] . No doubt the question whether something done effects an improvement upon land within the meaning of ss. 85 and 88 must be answered from a practical point of view and having regard to the use of the land made or intended by the taxpayer. Moreover an improvement on land may be made by removing something from it, as by clearing timber or eradicating noxious weeds: McGeoch v. Federal Commissioner of Land Tax [3] . Thus to bulldoze the surface of land, thereby removing rocks and flattening hillocks, might well effect an improvement upon the land. But in those cases the work done improves the land on which it is done. The singularity of the present case lies in the fact that the work of dredging, although done on the seabed, did not in any way enhance the value of the seabed. The seabed was not used by the ships that sailed over it - they used the channel. The act of dredging improved the channel - it did not enhance, and for that matter, so far as it appears, it did not depreciate, the value of the seabed. It may be true to say that the right to dredge was valuable, but it does not follow that the seabed had any value. There is no evidence that the seabed did have any value apart from the fact that a channel might be dredged in it, or that, if it had any such value, it was increased by dredging. The argument for the appellant is based solely on the value of the seabed in relation to the channel. However, the seabed, regarded separately from the water above it, had no value from the point of view of navigation either before or after it was dredged. Before it was dredged it was an impediment to navigation and after it was dredged it no longer constituted an impediment but in itself it remained useless and valueless. For these reasons I respectfully agree with the statement of Brennan J. in the Federal Court [4] : "The land, notionally separated from the water, is made no more efficient for man's use, and no more valuable, by dredging." The position might have been different if the sub-sections had spoken of improvements upon or appertaining to land the subject of a lease. However, the sub-sections refer only to improvements upon the land and the expenditure presently claimed is not in respect of improvements of that description.