The regulation of the motor in this case should be accomplished by the conditions of pressure in the pressure tank, as is the case with a steam pump employed in this service.

The next application of importance on the list is sewing machines. In the tests I have been able to make on this class of work I have obtained some singular results. One item of importance is the fact that the single thread machines, which are lightest running, consume the most power in operating. Paradoxical as this may seem, it is easily explained. As a rule this class of machine is used on light work, such as shirts, ladies' underwear, etc., and operated at a higher speed than any other class of machine. At equal speed the volts consumed on a single thread machine as compared with a shuttle machine is about as 2 to 3. In average commercial use, however, the positions are reversed, and the ratio of volts consumed in the single thread as compared with the shuttle machine is about as 5 to 3. To double the speed on a sewing machine requires about 2½ times the power. The difference in volts consumed on the different makes of sewing machines is so small that we may disregard it entirely, as well as the character of work done by the machine, for the heavier the work the slower the speed, and more frequent and longer stops on the machine, thus keeping the average volts per operator about constant in all cases.

This leaves the speed in stitches per minute at the sewing machine the factor from which we must calculate the power required in a sewing machine plant. To illustrate this I will give you the record of two cases which are about the average. Case No. 1 is a shop in which are 30 sewing machines connected to a 2 H. P. motor. At the time tests were made there were but twenty operators at work, leaving ten idle machines, the entire shafting, however, being in operation. The class of goods manufactured in this shop is a cheap grade of cotton and wool pants, rather heavy goods to sew. A volt meter across the terminals of the motor gave the following readings with the current at 9 amperes: Minimum 90 volts, maximum 148 volts, average 119, which gives us a minimum average per operator of 4.5 volts and a maximum average of 7.4 volts, or a general average of 5.9 volts per operator. This motor was driving the shafting for 30 machines, and as the average operators employed the year round will not exceed 75 per cent. of the shop capacity, it will, I think, be entirely fair to estimate the average volts per machine rather than per operator, as the user of the motor has contracted for power sufficient to drive his entire plant.

In this case, then, we have a minimum average of 3 volts per machine and a maximum of 4.9 volts, or a general average of say 4 volts per machine. A 2 horse motor of 82 per cent. efficiency with 9 amperes of current will require about 200 volts to develop 2 actual H. P. Two hundred volts therefore is what the electric light company contract to deliver, while, in reality, they deliver only 129 volts or 60 percent., or a minimum average of 90 volts or 45 per cent. of the power contracted for. These machines were making about 1,200 stitches per minute - an average of 4 volts per 100 stitches.

Case No. 2 is a shop in which there are 32 machines, running about 1,200 stitches, each being supplied with an individual motor of 1/8 H. P. capacity, and the class of goods manufactured being men's summer clothing, such as white duck vests, flannel coats and vests, etc., the duck from which these vests are made being about as hard work on a sewing machine as can be found. In this shop were 24 operators at work. The maximum volts in this case were 116 and the minimum 40, or general average of but 78 volts, or about 2½ volts per machine with 4 more operators than in the first case, in which we had an average of 119 volts. This shop has been paying the electric light company $32 per month for more than a year, which is the price the company charge for current for a 4 H. P. motor which approximates 400 volts, the company contracts to deliver. This gives us a minimum average use of but 10 per cent. and a maximum of 29 per cent. with a general average of 19½ per cent. In other words, the company is saving in this shop the price of a 1/8 H. P. motor each month, besides making a profit on the volts actually delivered.

On a contract for three years the electric light company would be money in pocket if they would present the customer with 30 small motors, charging him $1 per month per motor for current, rather than let him buy a 2 H. P. motor to operate the same machines with the necessary shafting at a charge of $18 per month for current. Taking this average in case No. 2 of 2½ volts per machine, from a 50 light machine, we could run not less than 900 sewing machines, or about 18 to the arc lamp. At $1 per month per machine an income of $900 per month would be derived from a 50 light machine without any lamp expenses, such as carbons, repairs on lamps, globes, etc. On the average, in case No. 1, of 4 volts per machine, we could operate but about 562, say 600 machines. Divided up in shops of 30 machines and a 2 H. P. motor to each shop, we would have 20 two H. P. motors. At a charge of $18 per month each, we would have an earning capacity of but $360 per month from the same 50 light machine.

This is but one page from the thus far unwritten history of the much maligned small motor. Still the question is frequently asked, "Can we sell current for $1 per month for a small motor driving a sewing machine and make a profit?" As a matter of fact, 50 cents per month for small motors driving sewing machines yields a better profit to the company supplying the current than $10 per month per H. P. in large motors to drive the same machines, besides the immense advantage which the small motors possess of keeping the circuit in much better balance, the fluctuations due to the stopping and starting of large motors being at times a serious matter. One electric light company, making rather a specialty of these small machines, rent the motor and supply the current for $1.25 per month per sewing machine, and report that at this price the motor pays them a better percentage of profit than their lamps. This company have some 200 small motors on their circuits.