New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1891-11-26
POPULAR OBSERVATIONS.
NETWORKS WATER SUPPLY.
GENERAL GREELY on THE sITUATIoN-THI
AVERAGE RAINFALL. OF RECENT YEARS.

NEW 1OhhSS WalEh SOIILls
GENERAL GREEDY on THE sITUAToN-THE
AVERAGE RAINFALL OF RECENT YEARS.
TO the Editor of The Tribune.
Sir: In connection with the present water scarcity
in New-York, have watched with some interest for
an application OF meteorological information to practical
purposes. 1t is evident that the American mind OF to-
day is especially practical. but this phase of the
question has not been, far as have seen, publicly
discussed. Although no longer in official reationS
with the Weather Bureau, yet venture personal
though brief and perhaps incomplete statement OF te
normal average rainfall regime Of the Croon waeer
shed. j have available the rainfall records for seven
teen years by the Signal Corps at Newfork Clty' anu
for sixty years at Troy. These latter observations
were furnished by courtesy Of Mr. b. H. Baermah' ehe'
engineer of the Troy water works IL mas oee"
assumed that these two records indicate closely the
rainfall Of the Croton and other tributary
but owing to the nearness of New-NorK Cl,y ns ~
scrvators have been given doUbl. weight CohDn'ine
the observations ii appears that the average ii ,
for each day of the year amounts to one huhdreu au
thirteen thousandths (113) Of an inch IL Is uuq"a"'
distributed, however, since from hity 10 sAN P
cenum more rain falls at Ncw-fork Ill Jny anu -'suo
than In May the month of least rain Al Troy seNenN
per centun more falls In July lhin al 'e''""''' Wv
driest month at that point. ,
From the combined records the average day raii'i'
for the Croton watershed in thousandths OF an nc e
month Is as follows January, ITO; feOruary' 40
March, III; April, 1o4 May, 90; june lio' july
40: August 1879; september 1o' OCTOBER ioe NJ
yember III December and for the whole year. 40.
II IS TO be noted that the surplus water falls almost
entirely during July and August the average excess
for these sixtytwo DAYS amounting to twentyslA anu
half thousandths daily or l.043 inches lor te "oo
period Engineers Others cognizaht OF the ara u
the catchmant basin can compute now much inns
means to New York in the way OF water III Is eVue'
that this scarcity coming almost Immediately after Inc
fail
when IL is not probable that the deficiency can pe
made good from natures action. The daily average
of .113 inch cannot be reasonably iooheu ior UNI"
February and in the meantime, unless there Is an eA
cess OF rainfall the month of December VIII be mafheu
by daily deficiency of "Ol4 inch, or 434 men Tor lhe
whole MONTH January hardly holds its own, anu
although Its deficiency is nearly made up by the usual
February precipitation, yet the small deficiency Vi
March and the much important ones OF April anu
Nav are in prospect before the copiOuS rains oil sum
mer come TO furnish surplus over ana ABOVE the
growing needs Of the great metropolis.
IL IS evident from these statements that the water
commissioners have acted none too soon or too rad
cay and IL would seem advisable that lberaily souu
pot he practIsed until sufficient surplus 10 tide over
The months of April and May is in sight. 1t Is true
that the December rainfals are sometimes heavy anu
according to the sixtyyear record vi Troy THIS occurs
one year in three. On the other hand the oehciehoS
of December is greater than that here gwen one year
ont Of two. The deficiency for December ana the
following January combined is greater than here gwen
three years Of four which reduces the chances Vi
rainfall abnormally great to in four. ,
The average annual precipitation OF New-fork CITY
0orty four inches in round numbers is remarkably con
slant The mean deviation is but per cenium so
that in dry year, such 1891 the dehclehey ougit
not to exceed four iches, or theTeaoous. inc pee'
wear has kept within these limits up 10 November l,
ut which date the deficiency from January was "a
inches by the Government record. This dehciehcy uocs
moi apply directly the Croton watershed, however,
since the rainfall for the year at Algany was III excess
for the same period 8 % inches. GIVING the YORK
observations double weight and combining them with
those OF Albany, would indicate that the decency l0r
The last ten months over the Cr0tOn basin amounts
only TO O4O inch, a very small amount, which clearly
indicates thahe present scarcity Of water Is not Que
10 lack of rainfall but TO other causes. .
IL this letter should assist in drawing attention 10
the Importance of rainfall regime as a subject Tor
systematic thorough study in connection with inc
water supply OF the greatest and most populOus Oh
American cities the time spent in Its preparation VIII
be amply repaid. A. w. GREELi'
Washington, ID. c., Nov. 21 1901.