The words of a written contract are the sole expositors of its meaning, except so far as they refer to something without the instrument. If another document is referred to — if, for example, a policy of insurance refers to an applica*362tion or survey, or to by-laws or regulations — the document referred to is to be construed in connection with the contract, and as a part of it, so far as the reference makes it such. If a custom or usage is referred to, the custom or usage is to be ascertained as in other cases by the proper evidence. If a term of art or trade is used in the contract, having a peculiar signification among persons conversant with the art or trade, the testimony of such persons becomes proper evidence to prove the meaning. These principles are to be applied to policies of insurance in the same manner as to other contracts.
Taking then the policy before us, we find in the printed form a provision referring to certain lists of property which are classed as hazardous, extra-hazardous, special rates, and not insurable; and the keeping of these articles in a building insured renders the policy void, “ unless herein otherwise specially provided for, or hereafter agreed by this company in writing, and added to or indorsed upon this policy.” Turning to the description of property insured, we find it to be “ their stock in-trade, consisting of the usual variety of a country store (except dry goods) and on their store fixtures.” The usual variety of a country store is thus provided for in the policy, and the defendants agree to insure it. But what such usual variety is can only be ascertained by parol evidence. We do not think that this construction of the language of the policy is changed by the special permission to keep burning fluid and gunpowder.
If then the plaintiffs can prove that oil, friction matches, earthen ware and glass ware, in such quantities as they kept them, compose a part of the usual variety of a country store, they have not violated their policy by keeping those articles. Elliott v. Hamilton Mutual Ins. Co. 13 Gray, 139. The parol evidence offered on this subject was pertinent and ought to have been admitted. So if the term “ store fixtures ” is a term of trade, commonly used among traders and insurers, and is used in such a signification as to include any or all the articles mentioned as such in the report, those were insured by this policy. The parol evidence offered on this subject was proper and ought to have been admitted.
*363The case of Lee v. Howard Fire Ins. Co. 3 Gray, 583, cited by the defendants’ counsel, differed from the present case in this respect, that there was nothing in the description of the articles insured that could, either directly or by reference, include a grist-mill. The cases of Macomber v. Howard Fire Ins. Co. 7 Gray, 257, and Withered v. City Fire Ins. Co. ante, 276, differed from this in making no mention of the usual practice, which these plaintiffs offered to prove.
Exceptions sustained.