This case is one of great commercial importance; has been elaborately argued; and has received the fullest consideration of the court.
*279The rights of the respective parties depend upon the contracts between them contained in the indentures of 1814, 1834, and 1856, which have been given in evidence; and the principal question at issue is upon the true construction of a single clause in the indenture of 1834.
In 1814, the plaintiffs, who were then as now the proprietors of the Long Wharf, and Ebenezer Francis, the owner of the estate now known as Central Wharf, under whom the defendants claim, made an indenture, for the purpose of establishing their boundaries, and creating and defining their respective rights in the dock lying between the wharves. By this indenture a division line was fixed between the estates, laid down on a plan to which it referred, and running the whole length of the lock. The limits of the open dock were also established, within which it was agreed that neither party should erect any build, ings or place any fixtures; and it was stipulated that neithei should “ permit any vessels to be stationary at a greater distance than sixty-six feet from their respective sides of the dock ” described, “ nor unnecessarily impede or obstruct the passage to and from any part or place within said dock.” Each granted to the other, and covenanted that there should thereafter be “ an open dock and common passage-way for all ships, vessels, boats and floats of every description, with free ingress and egress therefor, to and from their respective wharves and estates, and in and over the land and flats” described as constituting the dock.
By this instrument the boundaries of the two estates were settled, and the rights of the parties defined, as they now exist, except so far as they have been modified by the subsequent indentures. But it is very important to consider exactly what rights were thus established, in order more clearly to understand the modification afterward agreed to.
The leading object of the parties was manifestly to increase the convenience of enjoyment of their respective estates. This could be effected by using a part of them in common as a dock and passage, and devoting to that usé all of the interval between the wharves, except so much as might from time to time be *280required for berths, for vessels loading and unloading. Bach party would desire to use the part of the dock adjoining its own wharf for the purpose of laying vessels at the wharf, and to devote the whole of its own territory to that use, so far as the occasions of commerce might require, and so far as was consistent with a reasonable freedom of ingress and egress. The Long Wharf and Central Wharf were among the principal and most important wharves of Boston; and it cannot be supposed that either party intended to give up the right of access to them which the capacity of their own side of the dock would admit, for any vessels which the commerce of the city should employ. The distance between the wharves at the narrowest point would not permit the occupation of the prescribed width of sixty-six feet on each side for the berths of vessels, and leave a space between ‘them for ingress and egress equal to the width of vessels which then came to the port. But under the indenture of 1814, if larger ships than those in use between that date and 1834 had been constructed and used, there was nothing in the contract to prevent either of the parties from receiving them in the dock. And we are of opinion that, by the just construction of that indenture, the right to lay vessels at the respective wharves must have been regarded as so far subordinate to the right to a free access to the dock, that while vessels of any size might have been received and laid in the dock, provided the limit of sixty-six feet on either side was not exceeded, it would have been with an obligation to move them if the right of free and unobstructed passage required it. The indenture of 1814 did not limit the number of vessels which either party might place abreast at their respective wharves, except by the number of feet which they could occupy.
In consequence of encroachments on the dock made in violation of the previous agreement, the indenture of 1834 was executed. It sanctioned and confirmed all existing encroachments of either party, and authorized certain extensions of the wharves into the dock to be made. This permission was coupled with the condition that at the extension made by the Central Wharf Proprietors nearest to the entrance of the dock, “ no more than *281one vessel at a time shall ever be permitted to lay stationary at the berth made by said projection; ” and at a projection farther westward “ no more than two vessels abreast; ” and that at an extension of the Long Wharf which was authorized opposite the first named, the Proprietors of Long Wharf “ shall have the right to lay two vessels abreast and no more,” with a like right at another projection farther westward. It was farther stipulated that nothing in the indenture should be considered as authorizing either party to encroach upon or in any way obstruct the common passage-way of the dock, except as therein provided; but the said passage-way should remain open for the free ingress and egress for all vessels or craft to or from either wharf.
The plaintiffs’ case rests upon the proposition, that the restriction upon the defendants above recited must be construed to prohibit the occupation of dock room at the place specified for more than the width of one vessel of the size of which vessels resorting to the port of Boston were then built. In other words, they contend that the word “ vessel ” was used as a recognized measure of space, and that the object and intent of the contracting parties could not be accomplished by any other rule of interpretation.
The reasoning in support of this claim is certainly forcible, and entitled to great consideration. But after giving it all the weight to which we think it entitled, it is not satisfactory to the minds of a majority of the court.
It is not, in the first place, the literal import of the language used by the parties. Under the indenture of 1814, either party was at liberty to place as many vessels abreast as they chose, if they did not collectively exceed the limitation of the sixty-six feet. If the vessels were small, they could place more of them. If they exercised their full privilege at the narrowest part of the dock, it would be subject to the necessity of moving some of the vessels whenever it was necessary to give an unobstructed passage in or out. The object of the restriction in 1834 was undoubtedly to compensate for the' reduced width of the dock occasioned by the new projections, by limiting the space to be occupied by stationary vessels; and we are asked of what avail *282it could be for this purpose to limit the defendants to one vessel, if that one was to be as wide as any two had ever been, and might singly occupy the whole space permitted under the previous indenture ? .The answer must be that there is no reason to suppose that in 1834 the parties contemplated the increase in the size of vessels which has since occurred. If they had foreseen it, we have no means of knowing how it would have affected their agreement. Whether either party would have consented to exclude from a part of their dock and wharf any single ship of a kind which might be found best adapted to the purposes of commerce, may well be doubted. The change in the dimensions of vessels which impairs the force of a restriction expressed in the terms which the parties chose to employ, might, if foreseen, have prevented them from using any other than the very phrase which they adopted.
In the next place, it must be remembered that the stipulation as to laying one or two vessels at the places indicated in the indenture is in the nature of a restriction, and not of a grant. We do not understand it as affecting the provision in the indenture of 1814 that no vessel should be stationary at a greater distance than sixty-six feet from the respective sides of the dock. All the provisions of that indenture continue in force, except so far as they are expressly controlled by the subsequent contract. The limit to one vessel is of value, because while some vessels are larger than the largest then in use, others are smaller; and by the literal and express terms of the agreement, but one vessel can be placed where it is so stated, even if it is but fifteen or twenty feet in width. The parties may have regarded the probabilities as to the average size of vessels, and chosen rather to limit the number than to define the space to be occupied. They had a right before to occupy sixty-six feet. They agreed for the future that but one vessel should be stationary there, whether it occupied more or less of the sixty-six feet. There is therefore not only a possible, but a practical and natural operation which can be given to the agreement, without changing its terms.
But there is another consideration which should not be over looked, and which has a strong bearing upon the constructioi? *283to be adopted. The men who made the contract knew very well the size of the vessels which were then in use. In the indenture of 1814, the space to be occupied by vessels had been distinctly defined by measurement. Measurements are given in the indenture of 1834. The parties had minute surveys and plans to which they refer. If they had meant by “ vessel ” a space not more than thirty-five feet in width, to be occupied by one or more vessels at the pleasure of the respective proprietors, it would have been easy and natural, and in conformity with the previous practice, to say so. But, instead of fixing any measurement, they use the phrase “ one vessel,” and accompany the use of it by the stipulation that “ all vessels ” are to have free ingress and egress to and from either wharf.
It is a rule of frequent application in the interpretation of contracts, that the court must not only consider the purpose which the parties intended to accomplish, but the mode in which they have chosen to attempt the execution of their purpose. If their intent is made effectual at all, it must be by the means they propose. If an unforeseen change of circumstances makes those means less effective in producing the desired result, it will not do for the court to substitute others, to which the contracting parties have not assented. Thus in Hunt v. Rousmaniere, 1 Pet. 1, the parties had agreed on a security for a debt, intended to be valid and complete, but which, by the death of one of them, became inoperative ; but it was held that even a court of equity had no power to decree another security to be given, different from that which they had selected.
The majority of the court are therefore of opinion that the main proposition upon which the plaintiffs’ bill rests cannot be maintained. The parties have not, upon a fair construction of the indenture of 1834, made “ a vessel ” a term of measurement, and they have each a right to lay one or two vessels at the parts of their wharves at which they are restricted to one or two respectively, of any size, provided that they lay them upon their own side of the dividing line between their estates adopted in 1814, and that they do not go beyond the sixty-six feet from the line of their respective wharves. Bill dismissed with costs.