Exercise 1. Rearrange the sentences in the chronological order.

1. Keppler invented the form of the refracting telescope, which has a convex lens placed in back of the focus.

2. Hans Lippershey has been given credit for the invention of the telescope in 1608.

3. In 1930 Bernhard Schmidt invented a third type of telescope, which uses a spherical mirror and a correcting lens.

4. In 1609 Galileo learned of the invention of the telescope, built a three-power instrument.

5. Jesse Ramsden, an English instrument maker, reduced spherical aberration in the Cassegrain design, having used a paraboloidal reflector and a hyperboloid for the secondary reflector.

Exercise 2. Topics for discussion.

1. The invention of the telescope was a great step in science.

1. Galileo and Keppler much contributed to telescope-making.

2. Why are there different types of telescopes?

TASK 2

Translate the text without a dictionary using terms given below. Pay special attention to the underlined sentences.