Sloping still-head

Sloping Still-Head.— The simplest and most obvious alteration that can be made is to change the slope of the tube so as to retard the down-flow of liquid. This may be done by bending the tube near the top and bottom so that its ends remain vertical, while the middle part slopes very gently upwards. 

When a long still-head is used, it is advisable to bend the narrow tube just below its junction with the wider one, so that the condenser may be vertical in position instead of sloping gently downwards. Much less space is thus taken up on the laboratory bench, and the receivers are somewhat more conveniently manipulated. 

Spiral Still-Head.—The efficiency is further improyed by bending the sloping portion of the tube into the form of a spiral, probably because a better admixture of the vapour is thus produced by this device the amount of liquid in the still-head is still further reduced. 

The only differences are that it endures for a shorter period of time and the vertical lines of the square wave are changed to the sloping lines of a sine wave. If the time of valve closure were exactly 2Lie, the maximum pressure rise at the valve would still be the same but the curves of the sine wave would all end in sharp points for both maximum and minimum values, as the time of duration would be reduced to zero. These references to square and sinusoidal pressure shock waves are based on an experimental pipe with the following data L = 3060 ft, internal diameter = 2.06 in, c = 4371 ft/s, V = 1.11 ft/s, Vc/g = 151 ft, 2Lie = 1.40 s, static head = 306.7 ft, head before waive closure = 301.6 ft, hf= 5.1 ft. For the square wave, the time of closure is 1 s, and it will be noted that the actual pressure rise is more than 151 ft. For the sine wave, the time of closure is 3 s. 

Fig. 1. Development of the gliding process in dysplastic spondylodesis a despite marked gliding of L5/S1, there is still a normal relationship of values between the sacrum and the center of the femoral head. This is expressed as the normal values of the sacrofemoral tilting, the sacral slope and the overhang, b Only with retroversion of the sacrum (pelvis) is there a significant change in these positional parameters...

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