Observations

Letter by H C Russell, 20 January 1891

Letter by H C Russell, 20 January 1891
Letter by H C Russell, 20 January 1891
Letter by H C Russell, 20 January 1891
Letter by H C Russell, 20 January 1891

112-115

Janry 20

My dear Ellery

Many thanks for sending enclosed photo. I was anxious to see it. [sic] but there are some details that I was equally anxious about. [sic] that are not shown.

One of these is the plate holder. [sic] and the photo does not show how the plate is held. The eyepiece like extension seems curious. Does it mean that this is an eyepiece to see when the star is in the middle?

I know also Gill’s control modified by Grubb, the letter tells me it is perfect for 20m: I wonder how it corrects the errors of the screw itself?

I see they have given you a micrometer to the painter: with which you can march over the sky. I see Gill has exceeded the 20 minutes ?? (are?)from centre limit, and says that with a limit of 40 minutes he can get all the stars he wants. I have got nearly all I want in 20’ radius And mean to go to 40’ for the rest. Another thing I wanted to see & could not; and That is how he provides for adjusting the focus and fixing it when got. Gill’s idea was a sliding tube drawn in by 4 strong springs, and the distance between main tube, and slide adjusted by a collar; an[d] which are a series of circular wedges.

You will see I have departed from this, which for an instrument that requires to be as accurate as a transit instrument does not seem good enough; I have 4 screws the length of the distance screws is arranged by one screw working in the other. [sic] and through both goes another screw which clams the sliding tube to the main tube as separated by the adjusting screws.

The definition of my photo …. is very fine, but the polish is very poor. I have told Grubb about it, and he admits there were some scratches which annoyed him.

You must have got the [promise]d photo of my mounting today, and our letters have crossed. I will send you a photo of the plate holder when I get it done and I think I sent you photos of the driving clock an[d] Control, if not remind me of my sins & I will mend.

I am in a fix about plates I asked Mauchey for advice about them many months since and got no reply. [sic] and long since I sent money to Christie and asked him to have it expended in plates, and sent to me but they have not come. [sic] and I have ordered a sample from M.A. Seed the American maker recommended by the Henry’s [sic] & Pickering. I am using. [sic] the extra rapid “Ilfords”. but they are poor for our work. They have however according to the photographer’s [sic] here, one very good quality, they never strip.

I have been trying experiments when there is a chance as to star magnitudes. [sic] and I find that 60m on Nargus gives one a great many stars which Herchel(?) did not see and 35m some which he called 16 mag. I have one of Orion which was exposed 16 minutes and gives a star which Hershcel [sic] calls 14th magnitude.

On the general question. [sic] I cannot see much that is satisfactory: and I am trying to wait patiently for the promise of instructions which are to tell us how to do everything.

I think there is much need for such a book when all the circumstances are considered and if as suggested we are each night to take test photos of the selected places and then wait till they are developed and examined before taking the working photos, it will cause great loss of time.

I would like to talk the whole matter over with you and wish you would make it an excuse to come up and see my telescope. There are so many points to consider and in which we must work together; that if you will come here first: I will go to you later on, for I fear we cannot square it up all at one meeting. They seem awefully [sic] slow in that old world, in making up their minds what is to be done. It is as if every fellow was waiting to see how the other would jump. I will send you a silver print of one of my plates so that we may compare results as to definition. [sic] which there is another point on which there is a good deal to be said. My tube is of steel the whole length. [sic] and a change of 20 degrees in temperature would make a change in length of about 0.015in and a change of 0.01 makes a decided change of focus what is to be done with temperature changes?

However I must shut up: having worried you enough I am sure; if you have taken the trouble to read so far.

Yours faithfully
HC Russell

I have been terribly busy over this photo work lately. My only excuse for a long silence. Photo enclosed with many thanks shall be glad to get a photo of it.

Related