Theory:

     “No. Do not suppress it but tone it down. Add many if’s and but’s to make your conclusion appear not so certain... I will exert all my influence with friends in other countries to make them exercise a similar restraint for a while.” 
 
     “For how long?”
 
     “Until this wretched comet is safely out of the way. Let us spend some time now to plan the details of this international conference. Shall we call it in a week’s time, here?”
 
     A week to plan such an important secret conference of international experts! James thought it an impossible task, but Sir John disagreed, and began to spell out details.
Explanation:
 
Sir John, being a responsible, professional, and honest individual, did not attempt to prevent James's work from being published, nor did he allow it to be published exactly as written; instead, he requested that James alter it with certain ifs and buts. As a result, the news would have less impact because the comet's crash would appear to be so unpredictable. John also promised him that he would use his power and position to do the same with other countries. James demanded to know how long such information would be kept hidden from the public. John said that he would continue doing what he was doing until the issue was fixed. He then asked John to assist him in planning an international conference that would take place in a week.
 
International Conference.jpg
International Conference
  
James was not certain that a conference could be organised in a week. He thought the meeting would be difficult because he had such a little time to gather worldwide experts and scientists from all around the world. Despite this, Sir John proceeded to lay out the plans for the global gathering. Sir John Macpherson's decision to arrange an international conference at Comet I brings the narrative to a conclusion but without a satisfactory ending. The author is expected to offer a solution to the dilemma of Comet Dutta crashing with the Earth in Comet II. Discoveries can sometimes be harmful.
  
Meaning of difficult words:
 
S.No
Words
Meaning
1.
Suppress
 To stop an activity by using your influence
2.
Restraint
Stopping or holding your activity often for a good reason 
3.
Conference
Conference refers to an official meeting between several people to discuss important things
4.
Modification
A small change made on things to look it better
Reference:
National Council of Educational Research and Training (2008). The Comet - I (pp. 73-80). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.