(d) The cost of value (at the option of the Contractor) of all plant, horses, lumber, timbers, tools, machinery and implements used in connection with said works.

II. On completion of the works on said premises and said building, the Contractor shall remove from the premises all such plant, horses, timber, tools, machinery and implements as are in serviceable condition, crediting the owner with fifty (50%) per cent. of the cost or value (at the option of the Contractor) thereof, as originally charged hereunder. No credit shall be given to the Owner, however, for any lumber or timber which is under ten (10) feet in length.

III. There shall not be included in the cost of performance any interest on moneys, office rent, the services of any walking or visiting superintendent or any officer of the Contractor, nor the clerical or engineering services of the general office of the Contractor except as hereinbefore provided; and in determining the actual cost of articles, materials or items of every kind covered by this agreement, such articles, materials or items as are the subject of unpaid bills accompanying requisitions of the Contractor shall be taken at their net cost to the Contractor, and such articles, materials or items as are the subject of paid bills accompanying requisitions of the Contractor shall be taken at their gross cost thereof, without deduction for cash or trade discounts, rebates, allowances, credits or bonifications, (provided only that the owner shall have been given an opportunity of advancing the amount of the payment and of obtaining the discount).

IV. The Owner shall pay the Contractor's compensation in lawful money of the United States, as follows:

(a) On or about the fifteenth day of each and every month as the work progresses, the Contractor shall by due and proper requisition delivered to the Architect, specify the amounts paid for all the labor and the costs of all materials furnished during the preceding month, including cartage and labor in connection therewith, and also insurance premiums for insurance theretofore obtained, official fees, and cost of permits, expenses of Contractor's field office, and also the cost or value (at Contractor's option) of machinery theretofore delivered, including plant, and the reasonable hire or rental of apparatus theretofore incurred, and any other cost of performance. The Architect shall, within six (6) days thereafter, certify to the Owner the correct amount due the Contractor under the requisition, and the Owner shall pay to the Contractor the amount so certified on such requisition forthwith after the certification by the Architect, such certificate to specify that the labor and materials charged have actually been supplied by the Contractor and are then included in the construction or are located upon the premises, and that said other costs have been incurred, and that the cost or value thereof is proper. The Owner may, if it so desires, require the Contractor to exhibit paid invoices or receipts evidencing actual payment, which invoices or receipts shall remain the property of the Contractor; but nothing herein contained shall be construed so as to require the Contractor to pay any bills, accounts or expenses, except for labor performed, before being entitled to receive payment as the work progresses.

If the Owner should fail to pay to the Contractor, within five days of its maturity and presentation, any sum due it as a payment under this contract, or awarded by arbitrators, or if the Architect should fail to pass upon and certify to the Owner any requisition submitted to him as herein provided, then the Contractor may, upon five days' written notice to the Owner, stop work or terminate this contract and recover from the Owner payment for all work executed and any loss sustained upon any plant or material, and profit and damages.

(b) Upon the substantial completion of the work and within thirty (30) days thereafter the Architect shall certify such fact to the Owner, and if there are not then any amounts due and unpaid to sub-contractors, laborers, or material men, and if there are no mechanics' liens or other similar charges against the premises or the building, arising out of any fault or default on the part of the Contractor, which have not been disposed of by bond or otherwise, and upon the thirtieth day after completion, provided that such final certificate shall have been theretofore obtained, the Owner shall pay to the Contractor the final payment, which final payment shall include said Contractor's profit of ten (10%) per cent., the Contractor's additional precentage, as provided in the next succeeding subdivision of this paragraph, and any and all sums to which the Contractor may be entitled hereunder.

(c) In the event that the aggregate of the actual cost to the Contractor of performance of this contract and said profit of ten (10%) per cent. shall amount to less than..........., exclusive of compensation for extra work, the Contractor shall receive from the Owner as additional compensation, fifty (50%) per cent. of the difference between $........... and such actual cost plus ten (10%) per cent.

11. If at any time there shal be asserted any mechanic's lien for which, if established, the Owner might become liable, and which is chargeable to the Contractor, the Owner shall notify the Contractor thereof; and if the Contractor shall not, within fourteen days thereafter, have bonded or otherwise disposed thereof, the Owner shall have the right to retain out of any payment then due or thereafter to become due, an amount sufficient to completely indemnify itself against such lien or claim. Should there prove to be any such claim after all payments are made, the Owner shall notify the Contractor thereof, who shall have the right to use its endeavors to dispose of or to dispute or resist such claim, and the Owner shall render all assistance to the Contractor to that end; and should the Owner be compelled to pay any moneys in discharge of any such claim, made obligatory in consequence of the Contractor's default, the Contractor shall refund to the Owner all moneys that the Owner may be compelled to pay.