Goldmann, Sullivan and Labrecque. The opinion of the court was delivered by Labrecque, J.A.D.
Defendants appeal from a final judgment in the Law Division, based upon a jury verdict which awarded $13,500 to the infant plaintiff and $1,000 to her father per quod for injuries arising out of the negligent maintenance and operation by defendants of a mechanically operated hobby horse. Defendants' subsequent motion for a new trial was denied but the verdict in favor of the father was reduced to $725.50, the amount of his out-of-pocket medical expenses. The present appeal followed.
On January 6, 1961 the infant plaintiff, then aged 2 1/2 years, accompanied her mother on a shopping trip to the Woolworth Five and Ten Cent Store (Woolworth's), in Perth Amboy. In Woolworth's a mechanically operated hobby horse, owned by Kiddielane Corp. (Kiddielane), maintained by Automatic Concession Corp. (Automatic), and leased to Woolworth's, had been set up for use by the latter's customers.
The device was mounted upon a base and activated by a three-quarter horsepower electric motor through a vertical shaft, upon which the hobby horse was mounted. When a coin was inserted by a customer the motor went into action, moving the vertical shaft, with its attached horse, up and down. During each stroke (up and down) there would be a difference of 1 1/2 inches between the shaft's lowest and its highest position. The speed of the device varied from 45 to 110 revolutions per minute.
The motor was equipped with a gear box which had a large counterweight attached. The gear box regulated the speed of each stroke, while the counterweight was intended to produce a gradual, rather than a sudden increase in the speed of the machine. Thus, when a child would be put on the horse and a coin inserted, the machine would not attain its full speed for several seconds after it started. The "saddle" on the horse was equipped with a saddle horn (unmarked), which, when turned, would vary the speed of the up and down movement. The horse was equipped with reins and stirrups. There was no sign or instruction of any kind, either on or near the horse,
and no attendant to give warning or advice. Additional facts covering the nature and manner of operation of the machine will be discussed infra.
When the infant plaintiff, Barbara Ann, saw the hobby horse she asked her mother if she might have a ride. Mrs. Savoia lifted her on to the saddle and inserted a coin in the proper slot. The horse began to move up and down, as she described it, "real fast," with a "jerky movement." Although Barbara Ann was holding on to the saddle horn with both hands, she was "bouncing around" and having difficulty staying on the horse. As Mrs. Savoia was attempting to put her arms around Barbara Ann's waist to brace her, but before she could do so effectively, Barbara Ann lost her grasp and was thrown from the horse against an adjacent wall, striking a radiator as she fell and sustaining rather severe injuries.
Suit was instituted against Woolworth's, Automatic and Kiddielane, charging that one or more of them had so "negligently manufactured, managed, maintained, operated and controlled the said mechanical hobby horse that the same was caused to become dangerous, hazardous and unsafe as a result of which the infant plaintiff, Barbara Ann Savoia, was caused to fall," and seeking damages for her injuries and the expenses and loss of services sustained by her parents, Patrick and Helen Savoia. The jury's verdict was against all three defendants.
During the presentation of plaintiffs' case one Robert Traube was called as an expert witness. Traube testified that he was a "self-employed consulting engineer," licensed to practice in New Jersey for the past five years. He had received his engineering training at New York University and Virginia Polytechnic Institute, having been awarded a Bachelor's Degree in Civil Engineering from the latter institution. He was a member of the National Society of Professional Engineers, the Raritan Valley Society of Professional Engineers, the American Society of Civil Engineers and the Consulting Engineers Council. Prior to entering private practice he had been employed by the Pennsylvania Railroad, Pierson
and McWilliams, architects, and the Haller Testing Laboratories. He also had seen service with the United States Corps of Engineers.
Traube affirmatively stated that he was familiar with the "motion" of mechanically operated hobby horses, such as the one found in Woolworth's, and with the forces exerted on persons who would be subjected to such motion. Under cross-examination he admitted that he had never examined the hobby horse in question. Neither had he ever been involved in the examination or manufacture of mechanically operated hobby horses. However, he was familiar with the vibratory action created by their up and down movement. An objection to his qualifications was overruled, the court noting that he was an engineer with "experience and knowledge of harmonics and vibratory motion, which he has studied and to which he has testified."
In answer to a series of hypothetical questions Traube testified that, in his opinion as an engineer, the vibratory motion of a device of the type indicated created violent action and "dissonances" when the horse was moving up and down. As a result, a child would "bounce" up and down while the horse was moving. To prevent this, he was of the opinion that some kind of three-point stabilizing affect was needed.
He described "dissonance" and its effects as follows:
"Q. Insofar as this dissonance of which you speak, will you tell us in a vibratory motion what dissonance is?
A. Maybe I best describe it as an example. As you are pushing a child on a swing, for instance, if you are pushing with the same frequency, the same speed in which the child is going, the motion is rather calm or harmonious, but if you should suddenly change, push the child in opposite directions, the then motion would become violent. And in this case when the horse is going down the child is going up and when the horse is coming up the child is going down. There is a clashing or dissonance, which is the opposite of ...