Engineering teaches people to think in curves.  This youngster had to make a curve of the grocer’s trucking before he could visualize it himself.  His curve included factors like increase in stuff that had been hauled during the past three years and additions to the motor equipment.  When you have a healthy curve showing any business activity, the logical thing to do, after bringing it right down to date, is to let it run out into the future at its own angle.  This was done with the grocery curve, and its future extension indicated that not more than three months later the grocery house would need about four more five-ton motor trucks.

Closer investigation of facts behind the curve revealed an unusual growth in sugar hauling, due to the increase in supply and removal of consumer war restrictions.  And that grocery concern bought additional trucks for sugar within two months.  With the insight made possible by such a curve a salesman might safely have ordered the trucks without his customer’s knowledge and driven them up to his door the day the curve showed they were needed.

“Here are the trucks you wanted to haul that sugar.”

“Good work!  Drive ’em in!”

What has been found to be sound sales policy in the motor truck business applies to many other lines.  Yesterday the salesman of technical apparatus sought the customer with a catalogue and a smile—­and a large ignorance of the technical problems.  To-day that kind of selling is under suspicion, because purchasers of technical equipment have been led to buy on superficial selling points and left to work out for themselves complex technicalities that belong to the manufacturer of the equipment.

In the West during recent years a large number of pumps of a certain type have been sold for irrigating purposes.  Purchasers bought from the catalogue-and-smile type of salesman, hooked their pumps up to a power plant—­and found that they lifted only about half the number of gallons a minute promised in the catalogue.  Manufacturers honestly believed those pumps would do the work indicated in their ratings.  They had not allowed for variations in capacity where pumps were installed under many different conditions and run by different men.  The situation called for investigation at the customer’s end; when it was discovered that these pumps ought to be rated with an allowance for loss of capacity a half to two-thirds of the power, due to friction and lost power.

It might have been dangerous for the salesman to show up again in an irrigation district where a lot of his pumps were “acting up,” armed only with his catalogue and smile.  But when an engineer appeared from the pump company to help customers out of their difficulties, he won confidence immediately and made additional sales because people felt that he knew what he was talking about.

The superintendent of a big machinery concern found that his expense for cutting oils was constantly rising.  Salesmen had followed salesmen, recommending magic brands of the stuff; yet each new barrel of oil seemed to do less work than the last—­and cost more in dollars.