The work done and the physical consequences being improvements, are they "improvements on the land"? Improvements to land result in improvements on that land in the relevant sense. The preposition "on" does not here mean "on the surface of the land" or the like unless the word improvement is limited to physical objects placed or constructed on or in the soil, and for the reasons which I have given I do not think that the word has that meaning. But why then does cl. 2(d) refer not only to improvements on the land but also to improvements effected by the lessee or a prior lessee under the lease or a prior lease to the land? I think that the reason appears clearly enough. If the clause had referred only to improvements on the land this could have been taken to include only improvements made by the lessee. Why, it might then be said, should a lessee be able to remove or be paid for anything else? On the other hand, if the clause had referred only to improvements effected to the land by the lessee or a prior lessee under the lease or a prior lease, it would not embrace improvements made before the first granting of a lease. But prior improvements were envisaged. See cl. 1(j). There is not intended a distinction in quality or kind between "improvements on" and "improvements to" the land. All "improvements" within the meaning of that word, once determined, are comprehended. The lessee was entitled to be paid for all improvements, whenever they were done, unless they came within the particular exceptions stated in cl. 2(d). These exceptions were fixtures, erections and improvements removed by a lessee in pursuance of cl. 2(e) and those expressly excepted from the purchase by the lessee under cl. 1(j). Clause 2(e) allows the lessee on certain conditions to remove from the land any fixtures, erections or improvements thereon. I do not read this clause as referring only to a particular kind of improvement, namely, one on or distinctly visible or palpable on the surface of the land as distinct from one to the land. So also in cl. 1(j) wherein the lessee agrees to purchase from the Commonwealth for a price stated "such of the fixtures, erections and improvements on the said land as at the commencement of the said term were the property of the Commonwealth excepting boundary fence as shown on the said plan annexed hereto". This must include all improvements without distinction between those on the surface of land and those to the land. Otherwise there would be a most curious result. The proposed lessee would purchase all improvements "on" the land but would be compensated under cl. 2(d) for all improvements "effected to" the land not only by him or a prior lessee under the lease but also for any "effected to" the land by a lessee under a prior lease. Time and again the lessor would pay under cl. 2(d) for improvements prior to the lease which had not been purchased under cl. 1(j). They could not be excepted under that sub-clause because on this construction they could never fall within the sub-clause. I cannot conceive that such a result was intended by the parties in the operation of these clauses. I do not think that a qualitative distinction was intended between "improvements on" and "improvements effected to" the land.