64 MOUNTAIN OBSERVATORIES IN AMERICA AND EUROPE

Mont-Blanc(15,780feet),andtlierailroadwhichascendsfrom Manitouisa great convenience. For such observations as require a blue sky rather than good seeing, Pike's Peak (whennot surrounded by forest-fires) would seem tooffer

some important practical advantages over other mountains of equal altitude.

But^ifgoodseeingisessentialthepeak^isnottoberecommended.

Mountain-Sickness on

Pike's

Peak.

Professor Hale, 1893, reports that ^"

about

two-thirds of the tourists

who came up

^tlie

mountain on

thetrain each

morning were

affected

by

thealtitude,*

and

during our stay

we saw

one or

two

very seriouscases of mountain-sickness.

While

not

much

troubled, Professor

Keeler and

I

found

prolonged

hard work very

fatiguing,

and any

slight extra exertionat once increased the action of the heart"

Mrs.

Hale was

unable to

remain on

the

summit,

although she, natu- rally,

was

notcalled

on

for

any

extra exertion there.

Most mountains

are(for obviousreasons) quite cloudy(Pike'sPeak, Mont-Blanc,etc., as examples).

The

great

advantage

ofthe

mountains

of California, Arizona,

New Mexico, and Southern

Colorado is their

remarkable freedom from

^{clouds. I}

have

not

been

able to see

any

re- port of the conditions

on

the

mountains

of Algeria,

but one would

think, a priori, thatthey should

be

excellent.

Lowell Observatory, Flagstaff, Arizona

(7300 feet).

In the

American

Meteorological Journal for

March,

1895, Mr.

A.

E.

Douglass, one of the staff of the observatory, gives a table

with

numerical estimate of the ^quality of the seeing (its steadiness)

from September

28 to

December

31, 1894, while

he was

conducting certain very interestingexperiments

on

air currents within the tubesof large telescopes.

These

experiments

were

usually

made

only

when

the see- ing

had become

too

poor

for other observations.

The

seeing (steadi- ness) is

marked

in eleven grades; the best ^is10, theworst is 0. It is.

noteworthy

that the seeing

was worse

than 6

on some

part of

48

nights out of 51 nights recorded.

f

The

conditions at Flagstaff are, then, very different

from

those at

Mount Hamilton

(or

Mount Wilson) where

the

whole

night is apt to-

be good

^if

any

part of itis so.

At

Flagstaff itappears thata portion of nearly every night ^is unsatisfactory,

and

Mr.

Douglass

says that, almost the entire

month

of

December was

so.:}:

*Thetraintakes1hour45minutes to rise fromthe station at Manitou (6563 feet) tothe

summit

station(14,115feet). Thetimerequired for thejourney

down

is1hour¹⁵minutes. The

maximum

speedis8 miles,the

minimum,

3 milesper hour.

1 1havenot countedthe estimates for

November

2, 3, 4, 5,and9,wheretwoesti-

matesare given,onegreaterandthe otherlessthan6.

XInthisconnection, see a letterbyProfessor

W.

H, Pickering in the section ofthisvolumedevotedto theArequipaObservatory, page^40.

•\^ ^d

mountain observatories in america and europe.

65

Echo Mountain, California

(3500 feet).

A

private letter

from

Dr.

Lewis

Swift gives

some

statistics of the weather at

Echo Mountain which

I

quote

:

Between April 20 and December 1, 1894, there was only one rain of any amount, and duringthat timethe cloudynightshave averaged about threeper month. Thesestatistics refer,of course, to the Californiadryseason,themonths Decemberto Aprilbeing

much

lessfavorable. Butafter

making

all deductions

it is obviousthat the

number

of clearnights at Echo Mountain isvery

much

greaterthanatanyobservingstation east of the SierraNevada. Echo Mountain

(3500 feet)andMt.Wilson(4700 feet)arereachedbyrailwayfromLos Angelesand Pasadena. Mt.

Lowe

(6000feet) willsoon beaccessible inthesame way.

Chamberlin Observatory

(5400 feet)

near Denver, Colorado.

Professor

Howe,

Director of the Observatory, in aletter of

March

10, 1896, obligingly gives

what

data are available regarding the

newly

establishedobservatory.

From August

24, 1895, to

March

1,

1896

—

189

nights

— must be deducted

65 nights of

which no

record

was

kept, chiefly because the

moon would

interfere with comet-observations.

Of

the

124

nights remaining 71

were

utilized for

work

^:

I consider it safe to say that sixty per cent of the nights were clear. I believe the half-j^ear from September to March isclearer than from Marchto September.*

My

impressionof the star-images is that there ismore of dancingandshoot- ingoutof little arms than atloweraltitudes,but lessof blurring.

On

this ac- countfaintcompanionsnearbrightstarsarefrequentlyhardto see. . . .

I do not think thereare more than twelve orfifteen first-classnights in a year,butthisisa matterof estimationratherthanactual count.

The

transparency of the

atmosphere about Denver

iswell

known

to

be

remarkable,

and

isreferred to

by

Professor

Howe.

The National Observatory of Mexico (Tacubaya) (about 7500

feet).

On March

5, 1896, Iaddressed aletter to Director

Anguino

asking fordatarelating to thesteadiness of star-images at

Tacubaya,

based

on

experience.

From

his reply of April 9th the following paragraph is

quoted

:

Inrespect to the second question,theproblemiscomplicatedforus,notonly on accountof thealtitude,but because there is alocalcause that perhaps has moreinfluenceuponthephotographic images

—

thatis,the

movement

ofthedust constantly raised in thevaUeyofMexico.

As

yet

we

can say nothingthat would be

weU

established,sinceit isa point which I

am

yet studying,but

we

can advise you as

we

advance farther in the study.

*Theclearhalf-yearwouldbethe period ofunsteady images,so far as

my

per- sonal observationin thisregion holdsgood.

—

NotebyE.S. H.