Results of retail advertising must be measured by comparison; if a department store advertises handkerchiefs as a leader for Tuesday, _all_ handkerchief sales for that day would not be due to the advertising, but it is legitimate to credit advertising with any increase over normal sales. If correct sales records are kept, it will be possible to tell the exact amount of handkerchief sales for that and every other day in the year. [Illustration: Fig. 19. Detailed Record of the Shipment of Street Car Cards] A close check on returns can also be obtained by requiring each sales person to put a distinguishing mark of some kind on sales for advertised articles. Proofs of the day's ads, showing the articles advertised in the department, should be mounted on cards and hung in each department, that the sales person may know when advertised goods are sold. If made large enough, the card can be ruled for a tally of sales, and each sale of advertised goods tallied. [Illustration: A CORNER IN THE SALES ROOM AT THE CLINTON ST., CHICAGO, PLANT OF THE WESTERN ELECTRIC COMPANY] There should be an office record showing the results of advertising for each department. In comparing these records sales alone cannot be used, for the weather, and unusual events calculated to increase the crowds in town, must be considered. To-day's sales of an advertised article, with unfavorable weather conditions, probably will not equal the sales of the same article one year ago, which was circus day. If daily records, similar to that provided in the form shown in Fig. 18, are kept, they will soon become very valuable to the advertising department of any retail store. [Illustration: Fig. 20. Record of Street Car Contract and Net Costs] STREET CAR ADVERTISING Street car advertising is of a general publicity nature. It is intended, not to secure direct orders, but to influence sales by keeping the name of a commodity before the public. It is local in its effects, influencing sales only in the cities in which the cards are used. Street car advertising is now controlled by a small number of agencies, who own the space in the cars in the different cities throughout the country. Through one of these agencies, contracts can be made for space in street cars in any city in the country. The rate for street car advertising is based primarily on population, the _circulation_ consisting of the number of passengers carried. When the advertiser buys space, he pays for having his card appear in a specified number of cars, for a stated period. As a rule, the rate is for monthly periods, with special discounts on yearly contracts, and cards are changed each month. On certain contracts the agency will include extra service, without additional cost, by running cards in a number of extra cars, which are put on during the rush hours.