Dr. Sly has appealed to several other portions of the deed as furnishing an implication to support this contention. With every endeavour to follow his argument, if I could, because there is much in the reason of the case, apart from its purely legal aspect, that would tend to lead one to that mental position, I have not found any justification for the inference which is sought to be drawn from the rest of the deed. I think it is to be read according to the principle laid down in the two cases to which I have referred. Passing from the application to covenants generally of the principles laid down in those cases and coming to their application to coal mining covenants in particular, the case of Jegon v. Vivian[6] is very much in point. In that case Lord Hatherley L.C., in dealing with a coal mining lease, said[7]: - "It has further been argued, that giving the lessees power to do certain acts implies a covenant on their part to do them; but that is a complete inversion. The lessee has secured to himself certain advantages, without introducing any corresponding obligation." That is one of a class of cases like Eadon v. Jeffcock[8] and Lewis v. Fothergill[9], which exemplify the principle that, if the parties intend to bind one another to obligations which are outside the ordinary meaning of the words used in the covenant, it is their duty to express them in the document that they have together framed. So in the case of Jegon v. Vivian[10] it was held that, if the lessors intended to compel the lessees to work the coal from the deep, that is, to sink a deep pit, and not to work by instroke, they should have so provided. So here, if the lessors wanted the lessees to work the entire seam of coal, they should have stipulated for it in the covenant. We find no such words in the covenant, though we find expressions from which Dr. Sly endeavoured to draw the implication. But the principle laid down in the case of Hamlyn & Co. v. Wood & Co.[11] by Kay L.J. is that the intention of the parties is not to be left to inference, unless from the language and the circumstances there arises an inference so absolutely necessary to the general intent of the deed that it must be supplied. A covenant to work according to the best and most approved method is somewhat similar to a covenant to work in a proper and workmanlike manner, and as to the latter Lord Hatherley L.C. in Lewis v. Fothergill[12] made some reference to the principle of construction: - "A proper and workmanlike manner may not mean the best possible mode of working for the lessor, but it means in such a manner as shall not be simply an attempt to get out of the earth as much mineral as can be got for the particular purpose of the lessee, regardless of any ordinary or workmanlike proceeding. That is the extreme contention on the one side, and the extreme contention on the side of the landlord is to say that these words proper and workmanlike manner mean that the lessees are to take means the most expensive possible, and the least likely to produce profit for themselves, for the express purpose of putting the lessor in the best possible position at the time when the lessees give up the mine. Either one or the other of those views is extreme, and we must look to see what the landlord has done with reference to protecting himself by the agreement. The landlord must be supposed to have known through his agents what it was he was dealing with, and to have known what was the ordinary course of protecting himself if he wished to be protected. Now as to the two systems in question, the one of working by instroke, and the other of working by means of a pit, they occur continually in mining leases, and provisions are often made expressly upon that subject." As to the meaning of this covenant the two contentions which His Lordship thought to be extreme ones have been put with extreme vigour and ability on the respective sides of this case. It seems to me that the true meaning lies between. It is impossible to say that a covenant for working the seam in a proper and workmanlike manner or according to the best and most approved methods, means that the element of profit can be left altogether out of consideration, or on the other hand that that is to be the leading consideration. That would be to say that to work a mine in the best and most approved method would mean that it ought to be worked entirely in the interest of one or the other of the parties according to their extreme contentions. An analogy to a covenant of this kind is to be found in Jones v. Shears[13], in which there was an agreement to continue to work a colliery rented by the defendant, so long as it was "fairly workable." A breach was assigned in terms, and traversed. There was still coal, but such as it would not pay to work. Coleridge J. held that under those words the defendant was not obliged to go on working the mine "at a dead loss." That was not saying that profit or loss is the entire consideration, but that the covenant must be construed reasonably. So that the work is not to be abandoned simply because it cannot be carried on without some loss. There may be periods during the lease when the profits from the working of the mine under a particular system are large, while at other times they are small or perhaps disappear altogether, according to the market value of the coal. But the whole period must be considered together, or else there will have to be a different reading of the covenant at every variation of the market. In Griffiths v. Rigby[14], there was a proviso for cesser of rent if the coal, so far as it could be "fairly wrought," should be worked out and gotten before the expiration of the term. That is similar to the provision here with reference to the exhaustion of the mine and giving notice of the termination of the tenancy in case of that occurring. In that case Pollock C.B. said[15]: - "Profit is not the test whether this coal can be fairly wrought, though in one sense it is so, because the usages of mining are founded on what can be done advantageously. Fairly wrought means, that which can be fairly and properly gotten," (that is, I suppose, according to a fair and reasonable system of working) "according to mining usage, without extraordinary difficulty or expense." So that, while on the one hand we find it laid down that the lessee is not bound to work the mine at a dead loss, on the other hand he is expected to carry on operations continuously unless what it is endeavoured to drive him to do involves extraordinary difficulty and expense. In Lewis v. Fothergill[16], Lord Hatherley L.C., after stating the extremes of argument, did not, in dealing further with the case in which that covenant existed, define the meaning of the covenant in absolute terms, nor is it absolutely defined in any case cited to us. It is a matter of very great difficulty to define it. But one would say that a covenant of this kind must necessarily be interpreted with reference to the subject matter and the circumstances of the mine and the place. What would be a proper and workmanlike method in one district, might not be so in another. What would be proper in the case of a fairly defined and established seam may cease to be so where the seam narrows to a point of extreme contraction. And these are questions of fact applicable to the circumstances of the place and the conditions of the mine to be worked. In that aspect they are questions for a jury, to be decided on the evidence of those who have knowledge of the circumstances in question, and have experience in the working of mines. In the present case His Honor does not appear in his findings to have applied his mind to these questions. Finally, it may be gathered from what I have said and the authorities I have cited that this covenant cannot be taken to be an absolute covenant to work the whole seam. But it is a very material question whether, under the circumstances of the place and the mine, it would not be a proper and workmanlike method of mining to take out the coal below the "morgan." That depends wholly on circumstances, and no line can be laid down judicially upon it. If it had been intended as a covenant to work the whole seam in all events, it would have been so expressed, but that has not been expressed. But as it is in terms a covenant to work the mine according to the best and most approved methods of mining, it becomes the most material question in the case whether to work only the coal above the "morgan" and to take out the pillars as that work goes from stage to stage, instead of taking out the whole seam together, or instead of coming back while the pillars stand to take out the coal below the "morgan," is under the circumstances a working according to the best and most approved method. In deciding that question it is quite competent to take into consideration that no man can be expected to work a mine at a dead loss, and, on the other hand, to take into consideration the question whether the covenant did not cast on the lessees the burden of working the mine according to the best and most approved method, even though at times that might involve them in some loss. That is a question of evidence to which the Judge did not apply his mind as a question of fact.