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Re: (meteorobs) "Mr. Denning"

----- Original Message -----
> Does anyone have any information about Mr. Denning and his list that they
> can share with us?
>
> George Kelley

George,

Two articles I know of are:

"William Frederick Denning: In Quest of Meteors" by Martin Beech, Journal of
the Royal Astronomical Society of Canada, Vol. 84, No. 6, pp. 383-395, 1990.

"The Stationary Radiant Debate Revisited", by Martin Beech, Journal of the
Royal Astronomical Society, Vol. 32, pp. 245-264, 1991.

I wrote a couple articles for Meteor News based on the above. The text
follows.........

-Mark Davis


<--- begin --->
The Denning-Olivier Radiant Debate
Meteor News, Spring 1993, Number 101

An interesting period in the history of meteor astronomy occurred around the
turn of the century, and was centered on the debates as to whether meteor
showers originated from stationary radiants.

The debate of stationary radiants first began in 1878 with the publication
of the article, "Suspected Repetition, or Second Outbursts from the Radiant
Points; and on the Long Duration of Meteor Streams" by William Frederick
Denning of England in the Monthly Notices of the Royal Astronomical Society.
Using his own meteor observations, and those from the Italian Meteoric
Association, he believed that meteors originated from a point in the sky
which remained fixed in relation to the stars, and that produced meteors
continuously over one or more months.

The debate prior to 1900 centered over the fact that meteors coming from a
stationary radiant could not originate from cometary bodies as astronomers
thought they did.  Several theories as to how meteors could come from
stationary radiants were put forth, and with Denning tirelessly defending
his observations, the idea was generally accepted by 1900.  Partially as a
result of this work, Denning was awarded the Gold Medal by the Royal
Astronomical Society in 1898.  (It is interesting to note that it was
Denning who, in 1877, first identified the nightly drift of the Perseid
radiant.)

The idea of stationary radiants first came upon serious doubt shortly after
the turn of the century.  The debate moved to America in 1912 with the
publication of the article, "175 Parabolic Orbits and other Results from
over 6,200 Meteors" by Charles P. Olivier.

In this article, Olivier, who founded the American Meteor Society in 1911,
stated that "Stationary radiants appear to be rare if they exist at all..."
Denning's reply was that Olivier "has adopted a method of reduction which,
instead of exhibiting what the data really teach us, veils their actual
meaning, and at the same time unduly complicates and multiplies results..."
Olivier countered Denning's criticism with "...The word error as used by Mr.
Denning simply means my results differ from his own.  The more my
conclusions differ, the greater the error..."

For all practical purposes, the question of stationary radiants was put to
rest for good with the publication of Meteors in 1925 by Olivier.  The book,
using both observational and theoretical concepts, concluded the debate as
no one with the exception of Denning continued to openly support stationary
radiants after its publication.

The past several decades have proven Olivier to be correct in his disbelief
of stationary radiants.  However, Denning was a talented observer and his
observations were without question.  His mistaken belief in stationary
radiants was the result of his method of data reduction.  Denning thought
every meteor he observed could be traced back to a radiant and he normally
combined observations from several nights to determine his radiants.  Recent
experiments performed by Martin Beech led him to conclude "that not only did
Denning's reduction methods generate false radiants, they also generated the
phenomenon that he called stationary radiants."  Olivier did not combine
observations and did not believe that every meteor came from a specific
radiant, so thus was not able to identify stationary radiants in his data.

Denning never did accept the results of Olivier, and never stopped believing
in the validity of stationary radiants.  It is unfortunate that such a fine
observer as Denning was to feel bitter to the end, writing before his death,
"...if a man labours hard enough and correctly enough to gather
well-supported facts rather in advance of his contemporaries he becomes the
target for sceptics, as though his observations were either imaginary or
iniquitous..."

<--- end --->






<--- begin --->
A Love Affair With Meteors: William Frederick Denning
Meteor News, Summer 1994, Number 105

The Royal Astronomical Society of Canada (RASC) and the British Astronomical
Association (BAA), in celebration of their centennial year (1990), paid
tribute to the more prominent members who played a part in the distinguished
histories of these two groups.  One of these members was the English amateur
astronomer William Frederick Denning (1848-1931).
Denning was a keen observer of planets and comets, but it was his passion
for meteors that he is best known.  This interest was sparked by the Leonid
storm of 1866 which Denning witnessed, and continued until his death in
1931.  At the height of his career, he was elected a Corresponding Fellow of
the newly formed Astronomical and Physical Society of Toronto (APST, later
the RASC).

During his career, Denning submitted many articles to the RASC Journal, most
of which dealt with meteors.  His first paper, concerning the Leonid meteor
shower, was published in 1872.  A catalog of radiants was published in 1876,
followed a year later with a paper presenting evidence of the nightly shift
in the Perseid radiant.  During the 1880s, he was able to maintain a
publication rate of 23 papers a year.  It was also during this decade that
he began to cultivate his belief in stationary radiants.  (See Meteor News,
No. 101, Spring 1993, pp. 4-5).

In addition to these papers, Denning was also devoted to writing papers in
which he called for new observers and discussed how to improve the accuracy
of observing techniques.  His paper entitled "Notes on Meteoric
Observations" was read at the 16th meeting of the APST in 1892.  In the
article he wrote "The systematic observation of meteors forms a very
interesting branch of practical astronomy and it is one in which amateurs
may suitably engage with certain prospect of success..."  From Denning's
other writings, he appears to have been particularly interested in radiant
duration and location and the prospects of two station observations in which
the true path of a meteor could be determined.

Denning also expressed his love of meteor observing through his writing.  In
"The Claims of Meteoric Astronomy" published in 1913, he writes "The view of
a beautiful meteor...encourages the observer and makes him enthusiastic."
He often used quotations and poems to communicate these feelings.  It is
fitting we remember William Frederick Denning not only for his scientific
achievements, but for his pure love and joy of meteors.

 Bright falling stars I greet you with a smile,
 While you beguile,
 My loneliness, with pleasure pure and sweet
 In moment's fleet.

 Whene'er you come you bring a joyous thrill
 My soul to fill.
 Oh messengers from distant worlds! I yearn
 Your tale to learn,
 And I await, amid earth's frosted dews,
 Celestial news.

-FALLING STARS
 William F. Denning
 JRASC, 1915

<--- end --->





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