As with most prefaces, this is written after the main work,
but it is still intended to be read first. It should serve two purposes,
which I hope can be combined without conflict, the first to act in the
manner of a Shakespearean chorus, setting the scene for the main
play, and the second to allow the author to present a purely personal
view of the motives underlying this work.
Science has a multiplicity of definitions but the conventional
Concise Oxford Dictionary one of "systematic and formulated
knowledge's will suffice as a start. Karl Pearson, in his book
"The Grammar of Science" extends his definition to embrace the
scientific method. He states "the classification of facts, the
recognition of their sequence and relative significance is the function
of science ". He deprecates the idea that science is merely a
compendium of useful knowledge, and elevates the scientific frame
of mind (by which he means the forming of judgments based upon
facts, unbiased by personal feeling) as being sufficiently justified in
itself. This seems to me to be an essentially moral argument, for
the practice of logical thinking, which is my interpretation of Pearson's
"scientific frame of mind ", appears to invoke no necessity for
justification by results. This would not imply that all such results
of logical thought are necessarily good, in a moral sense, but I would
submit that intellectual freedom, both to reason and to dream, is in
itself morally desirable.
For most people, however, dreams and reasons must start
from a present reality, and in this case the reality has been a complex
problem in a disturbance of a physiological control mechanism. How
does carbon dioxide fail to stimulate the breathing in patients with
severe chronic bronchitis?
For the application of Pearson's definition it is apparent that
the facts which are to be classified must first be ascertained. What
are facts ? I have no full answer, for any definition must involve
truth, and real knowledge of truth eludes me. However, I can
substitute for this unattainable objective of truth, by using what I
believe is an honest assessment of scientific method. I may never really
know anything, but if I make an honest observation, and consider to
the best of my ability the possibilities of error in my observation,
in my submission, I have made a contribution whose value will depend
upon my abilities. My interpretation of this observation, or in Pearson's
terms, my classification of my "fact" and its placement in sequence
and recognition of its significance, will always be open to question,
but the care with which the observation was made must indicate its
proximity to infallibility. In this sense, therefore, I can merely state
my complete agreement with Gray "to those physiologists whose
imperishable observations provoke my perishable interpretations".
It would follow, therefore, that in my view the accuracy of
the observation or the "fact ", is of paramount importance. Nonetheless,
observations without thought for their use, or interpretation, are
unlikely to provoke a spirit of enquiry to seek new observations.
A science which seeks to establish facts alone would, in my view, be
In the present study the difficulties of the problem impose
their own discipline. To investigate a control system, it is desirable
to study the responses of the system to known variations in a stimulus.
To know about something properly, there is no substitute for
measurement, to paraphrase Lord Kelvin. In this problem, therefore,
measurements of both response and stimulus, and then attempts
to relate these in some mathematical form are made. However, the
basic problem lies in the possibility of error in these primary physical
measurements of both stimulus and response. Furthermore, the
accuracy with which we can measure these values, at least in the case
of the stimulus, is of the same order as that which provokes a response
in the stimulated system.
The manner in which I have attempted to face these problems will
be shown in the following pages. I am conscious of many defects in the
methods I have used, and my conclusions are drawn with a full knowledge
that they are only justifiable in so far as they take account of their
foundations in these possibly perishable observations.