680 BELL SYSTEM TECHNICAL JOURNAL 



where Tq is the temperature diflference at / = 0. 

 If 



the temperature difference from the sink is Tq = Tc at the cooler 



limit of the band. 

 Th is the temperature difference from the sink at the hotter limit of the 



band. 

 Pm is the maximum permitted input, then the cycling time for heating 



On cooling 



from which 



f=-e' *>') 



T = Toe-^'""^' (kl8) 



Tc = ^ log. ^\ (kl9) 



Acknowledgments 



A large number of people have contributed to the work described in this 

 paper. The program was carried on under the general direction of J. R. 

 Wilson whose support and advice are gratefully acknowledged. J. O. 

 McNally gave more specific direction to these efforts and is responsible for 

 many of the design features. We are greatly indebted to him for his close 

 support and encouragement. 



Members of the Bell Laboratories technical staff concerned with various 

 portions of the developments were E. M. Boone, K. Cadmus, R. Hanson, 

 C. A. Hedberg, P. Kusch, C. G. Matland, H. E. Mendenhall, R. M. Ryder 

 and R. C. Winans. R. S. Gormley of the Western Electric Company made 

 considerable contributions to the work on the 2K25. 



The mechanical design, construction and specifications for manufacture 

 were carried out by a group of engineers under the direction of V. L. Ronci. 

 This group included D. P. Barry, F. H. Best, S. 0. Ekstrand, G. B. Gucker, 

 C. Maggs, W. D. Stratton, R. L. Vance and E. J. Walsh. L. A. Wooten 

 and his associates cooperated in numerous chemical problems throughout 

 this work. 



The authors wish to make particular acknowledgement of the work of 

 two technical assistants, Miss Z. Marblestone and F. P. Dreschler, whose 



