We have not been able to find any further or other testimony reflecting on the money loss arising from the cancellation of the contract aforesaid and it is, therefore, apparent that the trial court allowed in full the twenty percent gross profits in each of the four buildings aforesaid. The admission of this testimony not only was erroneous but it is wholly insufficient to support the judgment. Gross profits do not mean actual profits. Gross profits are the profits which the contractor uses as a basis for his contract. They are always speculative in that they are subject to delays in the construction of buildings, in differences in the prices of the material to be used therein and in many other things which may occur during the progress of the construction of the building or putting in, as in this case, the heating and steam-fitting for the houses named in the petition. It is a general rule that prospective profits of a contract are not the measure of damages. This is so, for the reason that the contingencies of performance may and frequently do seriously change the estimate of the contractor. The claim made here for damages for the loss of the building contracts is a special claim for damages for a definite sum and the evidence is wholly insufficient to support that claim. For this reason the judg*258ment is reversed and the case is reminded to the Municipal Court for further proceedings acording to law.