9 Lindley on Part. 2d ed. 492; Holme v. Hammond, L. R. 7 Ex. 218; infra, sec 848.

bound by a personal service of this class, which service is to be performed and paid for in instalments, that portion of the work that has been completed before the incapacity intervened is to be paid for either under the contract or on a quantum meruit.1 A master's death, also, terminates his liability on a contract of apprenticeship;2 and a contract for the services of a farm bailiff, which by its terms is determinable by six months' notice, or payment of six months' wages, is dissolved by the death of the employer, without leaving any claim on the part of the bailiff to be continued in the service, or for six months' wages.3

In the Roman law, not only death, but loss through casus of the capacity of the employee, is a defence on a contract to render particular services, as where an artist who undertakes to paint a particular picture loses the use of his hand by an accident. Temporary incapacity, however, only vacates the contract when it extends over the period within which the services are to be performed. Of course, such personal incapacity is not a defence when the work can be done by a substitute, and the appointment of a substitute is practicable. - The circumstances, as is noticed by Mommsen,4 from which it is to be determined whether a contract of service is distinctively personal are various. It is requisite to take into account, in such cases, the personal qualities of the parties, the custom in similar cases, the local usage under analogous circumstances. The nature of the service itself is to be first considered; and this is brought prominently forward in L. un. sec 9, C. de caducis tollendis (6, 51). - Some contracts derive a distinctively personal character from the peculiar legal relations by which they are environed. Of these a marriage contract is an illustration; a hindrance in the way of one of the parties being distinctively personal, a substitute not being from the nature of things allowed.1 Insanity, therefore, is a defence to such a contract.2 - Another illustration is to be found in cases where one party bears a peculiar personal relation to the other party, involving duties such as the operae officiates which freedmen owed to their patrons.3 The principal distinction, however, rests in the character of the work to be done. Some services are. independent, from the nature of things, of the personal qualities of the employee, as is the case where A. agrees to pay a debt of B., or to buy an article for B. at a fixed price. The same may be generally said of mechanics. A man agrees to do a particular piece of carpenter work. The fact that he is taken sick does not relieve him if he has the opportunity to provide a substitute, but neglects so to do. On the other hand, a commission that requires peculiar artistic, literary, or scientific skill for its execution assumes that the work will be done by the specific employee, the substitution of another not being contemplated. Hence, when an author is employed to write a particular book for a publisher on a topic in which the author is an expert, or a specialist in surgery to perform a particular operation, sickness, producing incapacity, would be a defence to an action for non-performance, such sickness not being imputable to negligence. Certain parts of a particular work are distinguishable in this respect - as a sculptor may delegate some portions of his undertaking to others, while portions requiring his distinctive touch he must execute himself. By Mommsen it is declared, as a general rule,4 that the greater the discretion given to the employee, the more exclusively is the commission to be regarded as personal. With regard to mechanics, we have the following:5 "Inter artifices longa differentia est et ingenii, et naturae, et doctrinae, et institutionis. Ideo si navem a se fabricandam quis promiserit, vel insulam aedifi-candam, fossamve faciendam, et hoc specialiter actum est, ut suis operis id perficiat; fide jussor ipse aedificans vel fossam fodiens, non consentiente stipulatore, non liberavit ream."

1 Stubbs v. R. R., L. R. 2 Ex. 311; Fenton v. Clark, 11 Vt. 557; Patrick v. Putnam, 27 Vt. 759; Clarke ». Gilbert, 26 N. Y. 279; and other cases cited in Wald's Pollock, 370; and see Whincup v. Hughes, L. R. 6 C. P. 78.

2 Whincup v. Hughes, L. R. 6 C. P. 78. As to apprenticeship, see infra, sec 603.

3 Farrow v. Wilson, L. R. 4 C. P. 744; infra, sec 848.

4 Op. cit. 72.

1 See infra, sec 324.

2 L. un. sec 9, C. de cad. toll. (6, 51).

3 L. 9, sec 1, D. de operis libert.

(38, 1).

4 Op. cit. 77.

5 L. 31, D. de solut. (46, 3). Ulp. 1, 7, Disputal. - Mommsen, op. cit. 82.

In this passage the various gradations of skill in mechanical industries are expressly noticed; but at the same time it is treated as settled that the right of an employee to substitute another in his place exists unless otherwise expressly stipulated. And it is elsewhere directly stated that he who undertakes an opus, or a piece of job-work, may employ others to do it in his place.1 Hence a workman engaged in such a task must, if personally hindered, find some one as a substitute; nor, if such substitute can be found, can he set up his personal hindrance as a defence, no matter how inevitable was the casus that hindered him. This, of course, is subject to the qualification that no such duty of substitution exists when the employee was selected on the ground of distinctive qualifications of high grade, being the object of special confidence from the employer, and with no power of delegation given him in case of his incapacity to act. - As will be hereafter seen, the question whether the assignee of an executory contract can recover depends upon whether the duty is one which the assignor alone can perform.2