Observations

Letter by H C Russell, 25 January 1873

Letter by H C Russell, 25 January 1873
Letter by H C Russell, 25 January 1873
Letter by H C Russell, 25 January 1873

666

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Sydney Observatory
25 Janry 1873

Sir

The Government of New South Wales have granted a sum of money for the Transit of Venus.

From their Agent General in London you have, or will in a few days receive, a general order for an object glass eyepiece &c the focal length is there given 12ft but that was written before the receipt of your letter to Mr Kopsch.

In this letter I send you more particular instructions, and as much has to be done I will be much obliged if you will execute the order as soon as possible.

Please send also a description and Photo of the Position Micrometer and say when I may expect the order to be completed.

I want an Object Glass of the finest possible description [‘description’ has been crossed out in the letter] quality specially adapted for double star work, but at the same time as achromatic as possible.

[over]

The clear aperture to be 280 mille focal length must not excede [sic] 4065 mille and if possible be 3950 mille

The object glass to be mounted in a brass cell of which a small model will be sent.

I want also the Brass work for the eye end of the tube with rack tube not less than 130 mille diameter and having a motion in slide of about 400 mille all the Brass work to be as light as possible consistent with strength, and made for a wooden tube?

I want also (8) eyepieces four negative and 4 positive powers of each set to be above/about ?? 100 200 400 & 800.

Also Phograpic [sic] enlarging lens made specially for taking Photographs of the sun during the transit of Venus diameter of sun’s image to ??(110) one hundred and ten mille.

The Object Glass must be ?? to some competent person to be hereafter [named??] who will certify as to its quality before it leaves Hamburg.

In conclusion I may say that I hope Mr Schr?der will send me a ?? that will justify me in passing by Mr Cooke of York and other English ?? in/on ?? the worlds competition ?? during the transit of Venus ?? are ?? next ?? equal if not superior to any of the same size.

I have the honor to be
Your obedient servant
H C Russell
Govt Astronomer

Hugo Schroder
Optical Institute
Hamburg

The Photographic enlarging lens is not in the order for ?? the Agent General but I will send you the ?? working for it and some other things yet to be ?? through Mr Kopsch.

HCR