24. Detailed wiring diagram showing all parts of the recording apparatus, together with wiring to thermometers 42 25. Section of calorimeter walls and portion of ventilating air-circuit 43 26. Cross-section of bed calorimeter 46 27. Diagram of ventilation of the respiration calorimeter 57 28. Cross-section of sulphuric acid absorber 59 29. Balance for weighing absorbers 62 30. Diagram of absorber table 66 31. Diagram of oxygen balance and cylinders 68 32. The oxygen cylinder and connections to tension equalizer 70 RESPIRATION CALORIMETERS FOR STUDYING THE RESPIRATORY EXCHANGE AND ENERGY TRANSFORMATIONS IN MAN. INTRODUCTION. The establishment in Boston of an inquiry into the nutrition of man with the construction of a special laboratory for that purpose is a direct outcome of a series of investigations originally undertaken in the chemical laboratory of Wesleyan University, in Middletown, Connecticut, by the late Prof. W. O. Atwater. Appreciating the remarkable results of Pettenkofer and Voit[1] and their associates, as early as 1892 he made plans for the construction of a respiration apparatus accompanied by calorimetric features. The apparatus was designed on the general ventilation plan of the above investigators, but in the first description of this apparatus[2] it is seen that the method used for the determination of carbon dioxide and water-vapor was quite other than that used by Voit. Each succeeding year of active experimenting brought about new developments until, in 1902, the apparatus was essentially modified by changing it from the open-circuit type to the closed-circuit type of Regnault and Reiset. This apparatus, thus modified, has been completely described in a former publication.[3] The calorimetric features likewise underwent gradual changes and, as greater accuracy was desired, it was found impracticable to conduct calorimetric investigations to the best advantage in the basement of a chemical laboratory. With four sciences crowded into one building it was practically impossible to devote more space to these researches. Furthermore, the investigations had proceeded to such an extent that it seemed desirable to construct a special laboratory for the purpose of carrying out the calorimetric and allied investigations on the nutrition of man.